Guy around the corner used to work for the post office and bought a Mack tractor they were selling. He removed the 5th wheel and put a camper on it, and now he doesn't have to pay the road taxes. It's HUGE! I'll see if I can go over and take a pic.
I have a vintage travel trailer parked on my project property so I like your idea. Plan is to build another truck to haul the trailer. Driving this dump truck on the freeway makes me realize that my future hauler should have all modern suspension and drive train to make it freeway friendly. Advantage is being able to drop the trailer and take side trips without carrying all that baggage. If you do something with Airstream, check out all the Airstream restoration sites. You can do anything your imagination can dream up with those things and like our old trucks, they have way more character than a modern RV.