I think a two wheel drive prototype would be a great start. Except in very rough terrain the handling will be similar. Even with two identical vehicles we will probably have to make some tweaks of the sort we will need to go between 2WD and 4WD.
We gotta learn to go down the street before we start around the world.
BTW for those of you who are not familiar with Southwestern geography, Kingman AZ, where George lives, is in the same sort of country the challenge has to cross. He can literally test in his backyard (if it's big enough
).