4500 I use, Life Support, has a real good hitch receiver on the back. It is connected to the 4" 1/8" thick HSS bumper I had put on, and the next cross member in front of that. We use it for a bike rack, or a cargo platform. I have been asked several times if I use it to tow another trailer.
In Alberta, where I live, it is actually legal to tow a trailer with a fifth wheel trailer. I have seen some scary looking rigs going down the road.