I tow a 22' enclosed with a 2100 pound car, a 6'tall tool box stack, 4 sets wheels, cabinets, etc with a GMC Sierra 1500 with the 6.0. There's a way you can get the tow rating to 10K. I got around the 1500 part with air bags, that way I don't have to drive an oversprung truck around all the time. Mine is the "All Terrain" package that comes with Rancho shocks, uprated springs and some other stuff. Engine is making about 400/400 (Just a bit less).

The other option was the Tundra, which is an awesome truck. While they are both 1500s, a 1500 today is much more truck than a 1500 was a years back.

Another thing to remember is a good brake controller. Some trucks now come with one, but the prodigy unit I have is sooo good, I think I'd skip the factory one unless I found it was an Prodigy equivalent.