4X4 is good to get thru on occasions in an easier fashion!
A metal bodied , or commercial body ( ie built for goods use) 2WD is more than adequate for 95% of the time , unless going thru sand for long distances.
It needs to be separate chassis , with good ground clearance . The second can quite often be enhanced by fitting a "taller" tyre eg going from 265/75r16 to 255/85R16 . Rear wheel drive is generally a better option for simplification of drive train and better traction when hill climbing. Fitting a diff lock to the single drive axle gives a tremendous increase in traction , and a set of tyre chains will further enhance this to standard 4X4 levels in mud !
Modern coachbuilt motorcaravans are in nearly all cases totally unsuitable for off tarmac use . They are built very much inside very limiting weight constraints, and as such are engineered for a "light" usage only .
When using commercial 2wd vehicles you must "derate" them for this type of usage, this means if your "kit" and personnel needs 1.5 ton carrying capacity van then do it with a 3 ton capacity vehicle. This is due to the commercial vehicle in most cases also being designed and engineered for on highway use . By following this policy the vehicle is much less "stressed" and will usually suffer far less wear and breakages HTSH

__________________
Current : 2007 Mowag Bucher Duro 6x6 Motorhome , 2006 Sedici 4x4, 2007 Range Rover supercharged