I read something about where a guy did that to a kid's red wagon. I think the biggest change he did was take off the pull-handle and add a seat post trailer tongue, though it could probably be done with a rear-axle tongue as well. I tried to look at it just now but my browser said there was a virus on the site so I couldn't check and see everything he'd done. I'd really like to do that to the wagon I have, it's somewhat larger than a kid's wagon, and it was in the fashion of a covered wagon (but not the right colors). The cover was waterproof but it's now torn, so I'm itching to make a new one out of a white tarp to make it more realistic, it'd make a great bike trailer if I knew exactly how it was done, considering it can hold 250 pounds, which is 100 pounds more than what the average Radio Flyers can carry.