I'm spoiled, my current setup is a 2005 Ram 3500 Cummins QuadCab 4x4 (single rear wheel) longbed with a 28' enclosed trailer. I think the trailer, car, and gear in the trailer bring the trailer weight to around #10,000?
The truck tows great, but could use an exhaust brake in the mountian passes. The new 6.7L Cummins with the new transmission and Variable geometry turbo are really nice for towing, but use a bit more fuel. I have a few friends with the newer 6.7L trucks and they are nice, but I don't want to go into more debt when the 2005 is almost paid off and works great for me.

Before I had the Diesel truck and enclosed trailer, I had to borrow my friends 18' open trailer and I had towed it with several vehicles including my 1984 RamCharger 4x4, 1986 Ram 150 4x4, and a 2002 Ram 1500 with the 4.7L.
The RamChargers suspension and wheelbase made towing a challange even though I used it to tow my '69 Coronet Convertible from the coast of Utah to Colorado, but the 318 was struggling on the passes and overheated several times. The 1986 Ram 150 towed pretty good, just need to keep it under 90 MPH while towing. It's sort of scarry looking in the rear view mirror at the trailer swaying almost sideways at you! The 2002 Ram 1500 towed good with no real issues, but the 4.7L would down shift alot when going up hills.