Some unorthodox trailer sizes here. The latter two seem to be converted campers, which means they should be able to handle weight.
If we can get someone to help us look at these, I think we can get a good used trailer for cheap... possibly even considerably bigger than 8x20 if we use a camper conversion flatbed.
Edit: Sam, do you think your dad would like to look at trailers with us or you? Would you be willing to ask for his help in such a project? He's the only person I can think of who has a big truck and enough knowledge to recognize a good/bad trailer.