5th Wheel Hitch, Aux Fuel, and Air Bag Questions

I agree with the others on the lack of payload and rear axle/tire capacity issue of the 2500 truck, with so much weight going in the bed of the truck, plus family in cab.

You'll likely need to remove the aux fuel tank in order to keep the truck under the GVWR and RGAWR, once the hitch is in, family and other cargo are on board, and loaded trailer is hooked up. I doubt the truck will have any more payload capacity left over to carry the extra ~550 lbs of aux fuel and tank weight.