1939 Coe Would anyone like to hazard a guess as to what engine is under that hood? My guess is that is NOT a 454. (That would be a 216 Splasher from the Factory BTW)
I'll further venture that a loaded tanker weighs more than a 28 foot camper!
It's all about the gearing. The frame may or not be up to the task as you say. But there is no reason that a small V8 or a straight Six can't haul the mail. They did it for decades before diesels became the norm.
I think a Gear Vendors should be on your shopping list though.
