Boaty,
For the load you are hauling, I wouldn't consider anything less than an F450 chassis cab or F550 chassis cab with either a pickup bed installed by an upfitter company or custom flatbed. You've posted that your camper weighs around 6500 pounds, plus you have a heavy trailer you tow behind it. The camper alone is going to make any 350/450 pickup exceed the RAWR, plus you will need suspension improvements to handle the weight. Add the tounge weight of your trailer and you are way over the rear axle weight rating.
Go
here to compare the specs of the 350 to 450 pickups. Go
here to look at the specs for the 450 Chassis Cab and 550 Chassis Cabs.
The chassis cabs have the rear axle weight capacities you need for that big camper that the pickups just can't deliver. Heavier frame, brakes, springs, wide track front axle, larger fuel tank capacity. Yes, the engine doesn't have the power of the pickup models, but I've driven the F550 Bucket Truck PSD's at work, and they go up the hills on I-80 through the Sierras with no problem, and they weigh about 15 to 16k.
I drove a 2002 F450 Chassis Cab at work for 165,000 miles. Currently drive a 2011 F350 PSD SRW Chassis Cab now that has 94k+ miles on it. Chassis is much stronger than the pickup models and are made for heavy weight.
Rich
