Again, I know the boat you are in, I have the same truck just in a 2500 (same springs and tires, you just have an "overload" spring that doesn't engage until a heavy load is applied). I didn't get fooled by my dealer though, I knew what I was getting because it wasn't my first one. Your Mega Cab rode better because it was actually a lot heavier and longer with the same springs.
My suggestion would be to hook your truck to the camper the way you go camping and take it to a scale somewhere. Get the weight of the rear axle and compare that to the RAWR. The door sticker is the pressure that they recommend for a fully loaded rear axle. The tires capacities added together are even more than the rear axle's capacity. The tires are rated at 80 PSI to carry that capacity. If you are not running at full capacity and I'm sure you're not then I would air them down. I know it seems like a lot but There's not much else you can do without spending a lot of money. I have about 5K in my suspension but it rides like a half ton and hauls like a one ton.
