Actually it has more to do with being a single rear wheel chassis. The other vans have bigger payloads because they employ the use of dually wheels.
The Promaster has a GVWR of 9,350 lbs. That usually means on a conversion you'll have around 2,000 lbs left over for cargo. That is actually a lot for a small vehicle like this.
But you need to choose carefully. All those pretty wood cabinets and bulkheads are heavy. So the more you go for that kind of thing, the less cargo capacity you have. I'd be sure to get the actual dry weight of any van you are interested to see if the CCC will work for you.
My Travato weighs around 7600 lbs ready for camping, so I have a lot of margin. But that comes at the expense of cabinetry, and the ability to stuff them full of junk. The Pleasureway has ALOT of interior storage spaces, but no open area for cargo like the Travato. So which could be accidentally overloaded?
FWIW, the V6 engine is plenty strong for this weight class of vehicle. I've found the hill climbing just fine and the sure footedness of the front wheel drive preferable. The real 17mpg economy isn't shabby either.
