A kid in the neighborhood saw my MB so he built himself a hauler trailer to haul scrap metal.
He plans to hustle and sell enough scrap metal to build a MB.
Your weight factor is a killer. PVC pipe trailer would be a lot easier to pull, a better option would be using parts from this company https://makerpipe.com/ and electrical conduit.
If you could see it up close weight factor wouldn't matter. The kid used what he could find and didn't have a plan or a square. He did it with zero help. The 2x's were hand saw cut and hand nailed. The tire axles are attached whereas they have several degrees of negative camber and toe in but the thing does what he wants.
I'm damn proud of him even though it's a true Frankenstein creation. I'm hoping he sticks with this project. I wouldn't hesitate to help with a little money or building. He's just gotta show he REALLY wants this. The only thing that concerns me is these bikes can be dangerous. I know people are responsible for their actions but, I would hate to be or feel partially responsible for someone getting hurt.