Whatever your back up plan is, try it at the dock or in calm conditions rather than wait to test under duress. This kind of thing always seems to happen at the worst time, so know what to expect. If you are relying on a manual over ride on the windlass itself, then have a plan if for some reason that doesn't work, like a gear box failure or other non-electrical or hydraulic issue. After a few tests the ultimate back up plan may be "get out the bolt cutters/hack saw/ Sawzall !"
I love all chain rodes, but boy is it tedious manually hauling up 200 feet of it, and then of course, that anchor.
PS: Larry, always admired those Lighthouse units.