Von how good is a Unimog on the highway, I'm looking into building an expedition type RV. Don't plan on doing bogging like in these pics but we want to be able to go way off the beaten path.
In my younger days I would do an off-road prepped VW westy, but they're getting a tad small for the wife and I. Planning on 1-3 month trips for our retirement.

Lots of off road campers are made on Unimogs. Many of miles both on and off road done on them. Just have to get the right gearing for your use. There are quite a few sites on the internet that are all about that type of camping and trucks. Here is one of the bigger ones Expedition Portal Forum I have never done it, but my latest truck would work perfect for it, as top speed of 80MPH and very quiet on the road.

Ya gotta gas it man! Give'r hell! If you're gonna do it, ya gotta hit it like ya mean it and stay in it till you're through it. Anything less... and you're stuck.

Once you start using snow chains.... You won't go back to normal A/T