I wouldn't be looking at a 1500 truck at all if you intend to put a truck camper in the bed. 1,200 pounds dry weight is meaningless as nobody uses it that way. Add up the weight of water, propane, battery, food, clothes, gear, etc. Then add the weight of you and any passengers and pets. Then add the weight of any bolt on accessories like a winch, bumper, steps, etc. Then add the weight of tools, fishing gear, recover gear, etc. I would want a 2500 truck all day long to carry all that. You wouldn't need a diesel, that's for sure. So I'd pick the GM or the Ford in that order. The RAM 2500's with rear coils aren't too good for truck campers.