The range that the remote will cover on the electric ones is pretty limited. If you go that route, I'd try to make sure you've got one with enough line and check the range that the remote has.
You could probably swap the steel cable out with a rope and get more on the spool. It's only 320 lbs, not a jeep.
You're going to be hard pressed to find one that has more than 25 or 50 feet of line. Some of the big ones will come with 100 feet, but they'll be overkill for this appliation and would pull a humvee. Also the electric ones are usually 12 volt setups. This one could probably be made to work. I know I've seen "Shop" versions of this one at the store that can plug into electric.
http://www.harborfreight.com/cpi/ctaf/d ... mber=91727
Also, does it have to be electric? Looks like once you get it lined up its going to go straight when you start cranking. I know I've moved my boat in the grass before and it only wants to go the direction in which it is pointed.
http://www.harborfreight.com/cpi/ctaf/d ... umber=5798
If it were me, I would think about sinking a pole in the ground and using a block and tackle to pull it up. I'll be trailer sailing tomorrow and can try using my old seaway 5:1 to pull the boat up on the trailer. Now that I've got the new 6:1 low profile, I can do dumb stuff with the seaway.