I like the idea a lot: Put a truck camper on a diesel truck and you can still pull a cargo trailer (or a trailer with a dirt bike) behind it. Or even a boat.
The only apparent negative is that– after talking with a friend who is an RV expert– the truck campers can be kind of “tippy” in the wind. The other big negative is that if you’re stuck in grid-lock for hours (picture the highways leading away from New Orleans in the run up to Katrina) … you have no way for your passenger to use the bathroom or lie down and take a nap. With a Class C RV, they just get up and go in the back. So, definite trade-offs, but I think the truck camper idea is still worth merit.
Take a look at this article:
The Truck Camper As A Family Emergency Vehicle