I think your boat will be a bit over 500kg. Spend another 40 bucks and get a 4000 lb winch with dyneema cable.
Dont worry about making it removable you can replace the supplied securing bolts with theft proof bolts or just drill a couple of extra holes and hit the nuts with a spot of weld.
Why not run 12 v from your car battery to the rear of your tow vehicle and connect via anderson plug or alternatively just carry a small 12v battery in your car and use anderson plugs to connect.
Cheers
Ray