I'd love a 12V operated lunchbox that handles three ropes, and winds a line in 10-15 seconds. I imagine something where I attach the loop at the end of the rope to a hook on spool, push a button, and whirrrrrr, rope winds up. The other end loop gets attached to a stationary hook on the machine, I bump the winch to put a little tension on the rope, and the spool locks so the rope doesn't unwind while on the lake or bouncing down the road. When I'm ready to use the rope, I unlock the spool, pull out the rope (perhaps the skier in water is pulling), I pull the loop off the hook and attach it to the pylon.
A thread here from 2005
has a couple of dead links to automatic winders (see post #14). Perhaps the Wayback machine
has a archive of those links to give you some ideas.