My test trip with the trailer taught me a few things, that I corrected today. The wheels couldn't come off, the bolts that hold the wheel attachment on still get stuck on doors and corners, and there was also no spot to attach bungees. I solved the first problem with a long piece of scrap copper that I cut and screwed into the frame, and then ground down the screw heads so they were flush. I then took a radial sander to the copper to smooth it out, and ended up sanding the entire frame! It looks better than new now, and I coated it with spray sealer to keep it that way. I removed some wood from by the wheels and now there is space for them to come off, and I drilled some holes in the bed to attach my bungees.
The whole thing rolls great! The connector is smooth and can bend more than the bike can turn. I am looking forward to a nice big grocery run.