Thank you everybody for your interesting replies.
Thank you for your very valuable advise. I will probably go for the Geolanders when I'm changing my tires next time. I will definitely need good road manners because still more than 80% of the driving will be on road. I didn't think of buying new rims as yet but I will go for them when I have the cash. Will I have to modify the gearing and/or speedometer if I fit them. I am assuming that they will go on without a lift.
Anyway for now I will be running the standard alloy wheels. We are planning another big trip into the wild in August so these wheels can stay on for some time.
No, I WOULD NOT go with the Geolandar M/Ts if I were you. The sidewalls are too thin. I've gone through three tires because of sidewall punctures. Picked up a nail while sliding around in the snow off road. A piece of wire took out another during a shallow stream crossing. Something slashed the third - never could figure out what did that. All of these were from things I couldn't see, couldn't avoid - in fact, never knew they were even there. That is my point. Mud, water, snow and sand hide a lot of things that can damage tires.
As I said, find a good M/T with reasonable road manners with a 6-8 ply sidewall. Look for something that looks like the Geolandar M/T in tread design. There are directional M/T tires out there that are similar to the Geolandar but have a more durable sidewall.
Keep in mind that these tires are much heavier than street or A/T tires - this is going to increase stress on your rims, suspension and steering. So, what may be a fine rim on the street and with A/Ts might not work out so good with, say, a Interco TLS.
That is correct. You will need to install or have installed your own breather lines for the transfer case/transmission and front differential. Which may or may not require some machine work.
Your mechanic doesn't off road, obviously. When you submerge a hot object like a transfer case or differential that has an internal air space, it rapidly cools creating a vacuum inside the object. The vacuum draws water/crud from outside into the whatever-it-is.
Having breathers helps with this and - in theory - should completely eliminate this problem. However, a pinched line, cloged breather will prevent them from doing what they're supposed to which is equalize the inside and outside pressure.
Yes, depending on how long the trip is. It doesn't take long to trash wheel bearings and regular grease is useless when you mix it with water.
This is what I use and it works VERY well. I have Chevrolet (GM) hub/rotor assemblies as my '97 Sport has a Dana 44 and they don't seal very well so they always get water in them. I've been running this for 11-12 years and I've only had to replace two sets of wheel bearings.
Valvoline HP GreaseThis is good stuff for everything. Steering components, hubs, etc. Everything with a grease zerk.
Something like Amsoil, Valvoline, Mobil 1, Royal Purple full synthetic gear lube. Check what rating you need for the differentials, transfer case and transmission. GL5 and GL4 are not compatible - you CAN NOT substitute one for the other and on the older Sports the transmission took GL4 while the diffs took GL5. Check your owners manual.
Besides improving your miliage, this stuff can save your equipment if you do get water in something.
I don't pay much attention to snorkels. There are few places where I live that a snorkel is useful on my vehicle. My Sport sits so high as it is that I don't have to worry about sucking water in the intake.
Do. This is critical unless you want to have a basket case vehicle in a couple years. Tracing electrical faults and replacing wiring harnesses is horribly expensive and difficult.
Dang. That sucks.
It would have been more convenient if it came with electric fans.
You're on the right track (so to speak). That will work up to a point. It depends on how deep the crossings are and how long they are - and on whether you have to stop or stall out in the middle.
Remember, the only thing that makes your idea work is the distance and depth. If the water is up to the hood and you're in it long enough, the water will eventually fill the engine bay. You can't stop it from happening and I can't tell you how long that will take. My engine bay will fill almost immediately because I no long have an undercarriage to kinda seal the engine bay off. Yours will take longer but eventually it'll happen. And, you can't 'just go faster', either. As you probably already know, there's a 'magic' speed to crossings - not to slow and not too fast.
The really big problems show up if you stall out of have to stop 'cause you're engine bay will be full by the time you restart. Hence the snorkel requirement. A fan is basically a screw. If you immerse it in something more dense than air it tries to screw itself through the fluid - you end up with the blades 'pulling' themselves into the radiator. Seen it happen. You DO NOT what this to happen.
Nope. You can not 'stop' a mechanical fan. There's no magic release button. That's why anyone that does deep water crossings runs electric fans. You can shut them off.
OH, BTW, don't forget to clean out your radiator and A/C condenser after every trip. The fan(s) draw all kinds of mud and crud in through the front and eventually it'll build up and you'll have overheating issues. Take the fan shroud off and take a high pressure sprayer and spray from inside the engine bay in reverse of the normal air flow. Make sure you don't have crud building up between the radiator and condenser, too.
Something else that's a good idea in environments like yours with lots of mud and crud is replacing the stock radiator with a radiator with a lower fins per square inch count. A lower fin density on the same size radiator means that the gaps between fins is larger and less likely to plug up. I'm not suggesting you do this right now unless you want to couple it with swapping in electric fans, but it's something to keep in the back of your mind for the future. You may think this isn't such a big deal, but I've already had this problem on my '97 and I'm not in the mud all that often.
You'll need a little lift for bigger tires. Not so much to fit the tires, but you need room around the tires for mud buildup. I've had mud/crud build up in my stock Sports to the point where they have NO articulation left and I almost couldn't turn the front wheels. This isn't a problem unless you deal with a lot of mud - and then it's a big problem. This is one of the few areas where a body lift would be preferable to a suspension lift.
You need to understand what happens if you fill a wheel well with mud and then hit a bump hard compressing the wheel(s). There won't be anywhere for the wheel to go. It'll smack up against that mud and and push up against the fender skirts and liners causing damage. If there's little enough room and you hit a bump hard enough, you'll tear the entire fender skirt out. I haven't torn out a complete skirt, but I got close. Its not impossible or even unlikely.
After thinking about this for a bit, you might want to look at an OME 1.88/2" suspension lift and a 1.5" body lift. You're not looking for 'rock clearing' clearance here. You're looking to get the body a little more clearance around the tires. Even slightly larger tires take up room in the wheel wells and you don't have that much to start with.
Hmmm. Diff guard. I had my solid axle swap (SAS) done just before I had planed to address this problem so I never got to it. The Mitsu rear axle is very much like a Ford 9" and about the same size. Look for differential guards for Ford 9" axles. I don't think one would fit unmodified, so you have to compare measurements. But if you find one that you really like, it won't take much for a halfway decent 4x4 fabrication shop to build one.
In order: 1, 2, 3, 6, and 7.
Next, 4 and 8 need to be done together. 8 FIRST, then 4. Not the other way around like most people screw up and try to do. Include some heavy duty steel rims.
5 last. You might want to look into a skid plate for the front under the front differential as well as a skid plate for the gas tank.
#1 should include the engine, power steering and brakes. Full synthetic engine oil like Valvoline or Mobil 1 for the engine. Full synthetic brake fluid - which means you have to flush the entire brake system. Brake fluid acts like a sponge. An open bottle will wick moisture right out of the air. Full synthetic brake fluid isn't supposed to do that. This is important, 'cause once you get water in the brake fluid it'll start rusting everything inside your brake system. Very bad and VERY expensive.
Take a look at these ...
Breather and recovery tankThis is a good design for transmission and transfer case and differentials. They're really small. Unfortunately, the roll bar clamp is kinds useless and impractical. I'm going to get in touch with them and see if it's possible to get two direct without the clamps welded on, otherwise, I'm getting two and I'll just cut the clamps off and make some rubber hose clamp mounts.
Edward
Nice to see someone else with a 5-speed. I was getting kinda lonely. 
