I would suggest for him to consider a small Travel Trailer, some on the lines of a Scamp or a Casita or a FunFinder which could be towed by a sedan or a van.
Might be more to choose from & perhaps less expensive than a B Class.
TT could be left at an RV park & have a vehicle to get around in.
If planning on stealth camping in the "B" without using a park. There is a lot of hassle in having a shower, water, & a toilet to use in any RV, perhaps a little more in a "B".
Likewise, going with a conversions van, one would have to have a place to shower, etc.
I believe I'd go with a small trailer.
Eastern OK can get some cold weather to take into consideration.
Might check at RV dealerships, they are having a lot of sells about this time of the year.