Until recently, 4x4 traction was almost the exclusive prerogative of pure camper rigs or "reconnaissance" vehicles. Today there are some "price list" offers for more or less extreme "off-road" vehicles.
Mechanical foundations are usually Ducato or Citroen or Ford Transit Trail, Mercedes-Benz Sprinter or Iveco Daily in the version developed by Dangel . These are normally pure campers (the most popular size is 6 metres) or special vehicles.
I divide these vehicles into three categories: vehicles that use all-wheel drive to "get off the road" in critical situations or to overcome not-so-difficult dirt roads (usually they have all-wheel drive engaged), permanent off-road vehicles, more emphatic (usually permanent all-wheel drive and enhanced with ground clearance), extreme ones, real "reconnaissance" vehicles.
Of course, it's always nice to think of your camper as "unstoppable", perhaps someone who can survive for a long time in a hostile environment. But the question is: do you need it?
I opened this paragraph with a photo of my then camper (Laika in Fiat Ducato) on a dirt road (straight and tens of kilometers long) in Iceland, everything was fine. True, in Iceland it is nice to go "in", to the heart, to do some crossings: I rented a car to go to Landmannalaugar and made other trips in large cross-country cars (see the article about Iceland ) ) . Iceland has been one of my trips, of course if almost everyone was like that, maybe a 4x4 would be fine.