Back in the '80s I had a 25 foot Class C that my oldest son finally finished scrapping last week. It was pretty handy for things like hunting but the last few years the water finally got the better of it.
Later, we had a 36 foot fifth wheel but it was too big to get into most places I hunt. When the kids got older and preferred a week of kayak touring or backpacking to sitting in a campground we sold it.
The oldest son and I collect military Vehicles. He has an M109A3 chassis with a large aluminum box on it that used to house a water purification plant that he converted into an RV.
My off-road RV is an S-280 communications shelter fitted out as a camper. We boom into an M35A2C 2-1/2 ton or M813A1 five ton truck using a wrecker crane. The trucks are all 6x6s. My two trucks have PTO driven winches with 200 feet of cable for self recovery.
Here's a link to the S-280. Mine got the windows and appliances from the Class C RV and has a double bed/dinette with 6" memory foam cushions. The rooftop AC would have been way too high so it has a standard house AC unit in the front wall so it extends over the cab. I've still got to fabricate a brush guard around it.http://www.gichner.us/s-280.html
The trucks aren't really much wider than a dually pickup truck so the height is usually the limiting factor off-road.
The two deuce and a halfs get about 10 MPG and the five ton truck get about 6-7 MPG. Not exactly economy vehicles but there is a lot to be said for 6x6 in rough country and snow. With a with a full set of tire chains they will push snow with the winch and bumper.
With all that said, we have tent camped year-round and can get along just fine that way pretty much regardless of the weather. That will never be as easy as pushing one button to level the 36 footer and another to drop the awning for fast easy camp setup though....