This is simple and woks:
This is using - mobec unit very interesting:
scroll all the way to the bottom to see build
Here is the money shot hope Murph is ok with me posting his picture:
Your idea of using a PTO from the engine is different from these 2 keep us updated with pics - the 2 links provided have great pictures and you have to admire the thought and engineering that goes with them. Also a clutch arrangement instead of a locking hub will be different.