PTO Winch Adaptations

I recently bought an 10,000lb braden PTO winch off an old railroad truck. I was thinking to make a kind of semi-portable "donkey" engine by mounting the winch on a heavy frame that could be bolted onto a truck or trailer, or just chained to a tree.

http://t0.gstatic.com/images?q=tbn:A...mUOXF2IP_0TeV3

I was wondering if anyone has done this before. It seems to me that the ideal power source would be a 6.5 hp gas engine, driving a hydraulic pump, driving a hydraulic motor which in turn would drive the winch via a chain sprocket. You could adjust this to get the idea ratio, and could achieve smooth forward-reverse-neutral via the hydraulic control valve.