I rigged something up about fifteen years ago which I can't remember now how I went about it. I know that it required more turning radius than using the stock ones from commercial bike trailers. I bought a new Instep lightning model some years back and put over a thousand miles on it hauling mostly my little dog, Aaniimoosh, but also Indian kids. It was a good one. You have a better memory than I do recalling that post about Isaac.
I've since been on the lookout for bike trailers when I see them at yard sales and found one for about ten bucks that had a molded body of plastic on it, but a good hitch/mount set up. The dog refused to ride in that one because it wasn't like her old lightning model. I found another and different Instep model at the landfill last summer missing the wheels which I found donors for from a kid's 20" bike, That's the one I want to try to make into a sidecar for the dog. My brother gave me his lightning model which he rarely used so that is what the dog rides in now since it is like her old one. The molded plastic ones are loud and probably less comfortable, she endorses the Instep lightning model. Dog knows best.
Good grief, I have four bike trailers. The pitiful thing is if I saw another at a yard sale I'd be tempted. Or an old bike. One of my X's said that my favorite color was rust. Never saw a boat I didn't like or an old outboard motor. Old cars. Falling down, neglected barns. I think I have old crap disease.
Anyway, the commercial ones I'm familiar with hook to the axle and are easily removed/ put back on with a clip. The Instep is designed to flex (twist) at the hitching point so if you dump the bike the trailer remains upright as a safety feature. If you can find a dead bike trailer and use the hitch from it that would be a good thing. I'm sure there are ways to hitch to the seat post. Clever as you are, you've probably already made something. It really is cool hauling little people around, even ones with four legs.
SB
