Folks, the easiest and best way to achieve this is to simply buy a 4x4 truck and get a large slide in camper.
It is also possible to convert any american made van into a 4x4 fairly easily, but it's not cheap.
A truck w a slide in is the best option and affords the benefit of being able to off load the camper at a campsite and then be able to go off with the truck separately.
The power levels available in trucks are also much higher, so you could then also pull a boat or a trailer with ATVs and a boat etc.
Resale value of trucks is also good and if you're really into boondocking, which desiring a 4x4 would seem to suggest, slide in campers are a LOT cooler without ac than class bs. They have more windows to open and they are completely isolated from all of the trucks running gear which creates heat, unlike a class b.
They are also roomier for a given size because they are wider.
I have both an extended chassis high top class b Ford van and a larger slide in inside a 1996 dodge w a v10 gas engine. In almost every imaginable way the dodge setup is preferable. The only exception would be in a family situation where you do a lot of traveling, sightseeing out windows, because in the class b everyone is together in the camper and in the pickup truck arrangement the driver may be alone while everyone else is in the camper, and in that case the class b is also safer.
However for the single or couple that boondocks a lot versus sightseeing on the road a lot, the 4x4 pickup arrangement is almost always better, and it's also far cheaper if buying used and they're easier and cheaper to work on ESPECIALLY IF GAS POWERED. I never have trouble w my v10 gas, nearly 200 thousand miles and I just change the oil and antifreeze and it still runs like a raped ape. My friends got the newer hemi and it's the same story. The newer pickup diesels all tend to be lots of trouble and cost.