why not build a bed cage for his truck, with an extendable boom and the winch on that?
something like this...
mount the winch up on the top, near the back, and have a pivoting arm that sits flush on the top, for driving, and when you fold it back, comes back and up, on like a 30* angle or something, and the winch cable running up the inside of that, with a couple pulleys on each end... wouldn't be hard at all to fab up once the cage is built...
basically all you would need is a mounting point and a decent length piece of channel, with a pulley inside, on each end, for the cable to go over...
kinda like this deal, but ontop of the rack... and without the legs of course...
hell, you could probably make one of those that slides into your receiver... just make sure you don't exceed the tongue weight... keeping in mind that this weight is measured differently, as it will have a twisting motion, due to the leverage on it, vs a trailer's direct down motion... if you do go with something mounted to your receiver, you might want it to have an outrigger of sorts, so that a lot of the weight is transferred back to the ground
or you could do up something like this...