As to getting rid of the dual clevises, can I get away with just soldering one end so it can't rotate? If not, how do I get rid of a clevis...
You don't have to get rid of dual clevises. I always use clevises on both ends on purpose. The force transfer between a horn and clevis is about as perfect and efficient as it gets. I either solder or epoxy the fixed one. Both solder and epoxy work great. And clevises work excellently well.