Plan A:
Remove wiring from the winch along with the four corroded bolts from the deck plate. Whiskey Tango Foxtrot, nothing happens! Use a hammer and other nearby objects to encourage separation activities to commence soonest. Again nothing happens. Cogitate on a possible plan B.
Plan B:
The deck plate is really stuck. Squirt penetrating oil twice daily on every conceivable interface. On day three beat on the parts mercilessly. The deck plate still won't freaking budge.