In my travels since going full time I have seen, mostly Fords F450 & F550's towing faith wheels. I also saw a GMC 5500 set up for fifth wheel towing. I do not know their ratings, but they have to be above a 350/3500! And they appear, at least outwardly to be stout pickups! Are these rigs considered HDT/MDT's?
NC Hauler has a good point, even though we are full timers, we still have to go grocery shopping, Church, and sight seeing. So for me a pickup that I can easily park is toward the top when I am considering what to tow with!