Back in 2004, we had a custom made custom winch/lift for a Ranger. Here is the jest of how it was made. They made it like the winch/lift that would fit in the receiver hitch on a truck, but only it was a bit different. They took and welded a frame/base to it so that it would sit under the bed on the Ranger and in between the frame of the Ranger. The took the bed bolts loose and inserted it and then bolt it the bed and it back to the frame. This insert had a receiver hitch on it so you could put the winch in it. The winch was also made to pivot or turn so that when you cranked up an animal you could swing the lift around from side to side. This winch/lift was only about 6" taller than roof on a Ranger. I would crank a deer off the ground then swing head or legs up in the bed of the Ranger, then crank it back down into the bed. The Polaris Dealer on the east side of Uvalde made the winch/lift for us. Sorry I don't have any pics.
There have been a couple of old threads on here in the past few years on this also. Might try to search for them.

I use the game hanging syestem that goes in the receiver hitch. Just take out that one pin so once deer is in the air it will spin.

yeah I have seen those but I just dont want to have to haul it around in my bed when not in use - the idea of a boat winch makes sense though - I may check that out