Isn't an RV kingpin a smaller diameter that class 8. I know the pins on commercial trailers are 2" . I don't know 'bout RV pins. Then you'd have to deal with the brake issue. TTR/TLR use air , not electric. You'd probably have quite a hard time getting the two to sync up n work smoothly.
Not to say it can't be done, just why? At least a full size pick-up you could still carry a load of drywall, pavers or whatever household projects you got and pick up groceries on yhe way. Can't do that with a bobtail tractor. Plus plates and insurance on a commercial vehicle?
I think I'd roll with the pick-up. But if you're swayed towards a class 6,7&8 . You could always score an International CXT , I think is the model. It's a 4 door vocational chassis with a pick-up bed on the frame. Kinda rediculous but look sweet. They can be had in 4x4 or 4x2 stick or auto. I think they all have juice brakes though. Good luck in whatever direction you go with.
