That self-powered trailer is awesome. I would love to have one of those to move around a farm that had roads through it. Rigged right, one could make use of the tractor throttle and main clutch, needing only the transmission on the trailer. Power steering and brakes might be missed though, so having a compressor on the tractor would take care of brakes, and I suppose one could have a tractor-driven hydraulic pump for steering with quick connectors and some simple, effective way to bleed the steering at hookup time. This is the sort of Rube Goldberg / Heath Robinson project I'd fully be invested in : )