Here they are still trying to build a SERIOUS off-road vehicle with mechanical shafts driving from the power unit to the wheels. How about:
Using a power unit that drives a hydraulic pump, and have a hydrostatic motor on EACH wheel, with no mechanical linkage at all between the power unit and wheels? The hydrostatic motor would be mounted above the centerline of the wheel, driving a reduction gear that was keyed to the wheel hub, and the entire unit rides up and down with the deflection of the suspension?
Changing the power unit to a regenerative steam piston engine, fueled by propane or other petroleum fraction of high volitility (even natural gas?), with a condensation and recapture sealed system for the use of steam to water cycle.
With some attention to design, like using relatively large-diameter wheels, the center of gravity may be kept down below the tops of the wheel diameters, making the vehicle practically impossible to overturn. With the high clearances possible by moving drive components above the hub of the wheel, and with a long vertical travel on each of the wheel suspension systems, it would be possible to crawl across rocks that are now impractical for most designs.
We haven't even STARTED to design for the 21st Century, people.
Yeah, but would the chicks dig it? : )
Take a look at how the Unimogs were designed. Any time you build a vehicle as a 4wd tractor with the ability to go from a top speed of .09 mph in low low low gear to 46 mph top speed in high gear (20 speed transmission) and a totally sealed (pressurized) driveline to cross streams high enough to put water in your lap (the air intake to the 6 cyl diesel is above the cab), you have a real off road vehicle.
The hill (including side hill operations) climbing ability is legendary.