"CJs are cool, work very well. They suffer from rust damage anyplace where there is water, salt, air, sunlight . . . "
More truthful words were never written!
What you are looking for can be summed up on one word.
Early jeeps have Dana 30 front ends and they don't live in mud pits or with really large tires.
Dana 30 is fine for a trail rider that is going to keep control of the skinny pedal on the right, but absolutely NO ONE can keep one together in any sort of 'Extreme' environment.
Mid style or late 'Barbie' jeeps not only have the weaker Dana 30 fronts, but Dana 35 Rear diffs that fall apart for no apparent reason.
Rubicon Jeeps came with reasonable transmission, will accept good transfer cases, have Dana 44 axles front and rear, have fuel injected engines.
They are also coil spring suspension that are much easier to modify for 'Extreme' usage.
Everyone (aftermarket) makes something for the new Rubicons, and most of it works.
You can get a few catalogs and get nearly everything you need for making it a mud bogger right out of the boxes.
Having said all that...
I'm a trail rider. I'm not into rock climbing or mud bogging, so I don't need to start with 37" tires and move up to 47" tires.
I need stability over monster ground clearance, so I don't have a monster lift.
I need good low speed driveability over sheer horse power, so I run a stock engine that has been tuned for low speed operation.
Just like most things, it's in the application...
There are four basic types of off roading (and tons of overlap combinations)...
1. Rock Crawling. Rocks and vertical, lots of low speed wheel articulation.
2. Mud Bogging. Flat, fast and wet.
3. Desert Racing. Flat and Fast with a lot of very fast wheel travel.
4. Utility Transportation/Trail Riding,
You encounter a bunch of different obstacles.
This isn't how treacherous of a single obstacle you can get through/over, in a single, purpose built vehicle,
It's how much skill you and your vehicle have over a multitude of different obstacles...
Team work counts in trail riding also!