Plan on getting 19.5 rims and tires.
Why? I listed two Lance models that the truck can easily carry with stock tires, even considering additional "stuff."
If he were to expand his search beyond Lance, there are plenty of other models out there that can easily be hauled with a stock 2500.
Will they be huge 11' triple-slide McMansions? No. They will be a compromise.
Oh, and read your camper loading guide a little closer. The measurements for the "A" and "B" points of the COG range are the front and rear edge of the truck's box.
