The trailer looks good, but doesn't seem to be a huge improvement over the bobyak. I would probably suggest some triangulation of the tow bar, maybe back to the subframe mounts on your LC4, aligning the pulling forces lower. What about a 29" MTB wheel? If you stuck with 26", there are lots of cheap chinese big box store dual suspension bicycles you could pirate a swingarm/shock off of, if you wanted suspension. A lot of LD bikers swear by the suspended bob over the rigid original. I like your idea, but am not surprised that most has been previously patented. Personally, I would probably buy a closeout Bob, and modify it to suit my needs. Good luck with your project!