Here's how we did it on our 3TexasTrailers. We used 1-1/2" tubing for our frames. We refer to our receiver as the "stinger":
Of course, we haven't actually tested this thing with a real bike rack yet, so I'm very interested in your research. We thought we could even use it to pull two trailers, at least for short distances. Again though, we haven't actually tested it yet.
