hmmmm... I've seen a number of anchoring systems in use, but not many are off the shelf. Don't know if that's because they're not readily available or what.
I would think a 12-volt winch such as four-wheel-drive rigs have on the front (Warn?) might be all right if the retrieve speed is quick enough.
I would look up Three Rivers Marine in Woodinville, Wash., and see if they have a system. They have a website, 3riversmarine.com, I think it is. They do offer "river anchoring systems" for sleds, but I can't remember if they are motorized or not. Another option would be to contact Stevens Marine in Tigard, Oregon, or Willie Boats in Eagle Point. They might not have anything in stock but might be able to lead you to the place that would.