You guys missed that he's also looking to TOW.
It's one thing to be 1000lbs overweight with the camper if that's all you're going to have, but he's also going to be ANOTHER 1000lbs over with the tongue weight of the trailer behind him.
Dodge Megacabs are HEAVY HEAVY HEAVY right off the line, especially if it's a 4x4 Cummins Laramie with all the bells and whistles. Last empty weight I saw on one was over 8000lbs! They're so heavy even the 1500 series megacabs have heavy axles with 8-bolt hubs.
Throw 700lbs of people in the cab (even a relatively fit family of five is going to exceed 500lbs, and it's only going to get worse as the kids grow), and now you're down to <1200lbs of payload on a 2500. Now you're going to throw 3000lbs+ worth of camper in the bed and another 800-1000lbs on the receiver.
I guess if three times the truck's available payload capacity is ok with you, more power to ya.