I’ve had best success with neoprene shin pads stretched tight. For ultimate wheel Anthony Soumiatin recommends getting a couple pieces of leather custom made.
Regarding the frame, an unbike is a unicycle made from the front fork and handlebars of a bike, usually with BMX pegs to stand on. There are variations which substitute a unicycle seatpost for the handlebars and I don’t see any reason why BC plates wouldn’t work in place of BMX pegs. It should be easier to ride and I’ve theorized that this would make a good skatepark unicycle. You might see if you can find an old bike fork that’s the right size (width and tube inner diameter) and try it out. I’m planning to do something along these lines, making a unicycle from a drift trike front end. I’m planning to find someone who can cut a slot in the seat tube and then put a seat post clamp and unicycle seat post in. Some unbike videos are:
