I really like your hitch :D. I plan on building a bike trailer also. Suggestion ; Would it not be stronger to use bolts( instead of screws) on the tire mechanism with washer or metal plate to keep from digging down or possibly busting frame from weight? I have been trying to figure what material is lighter etc and what brackets I can use and I am going to wrap my frame with a sheet metal at the tire section to prevent breaks and make it stronger at that point and over the hitch. Great video.