I have an In-Step kiddie trailer that I took out the superstructure and floor out of and replaced with corrogated plastic (the stuff they make cheap advertising signs out of) for the floor.

I pull it with a geared bike sometimes and sometimes my winter fixed bike. Works just great. I can haul a lot of stuff with it. The winter bike is geared so low that I could be pulling a dead cow back there and not notice it.

jim