Great idea!
My wife and I had a boat in the Keys for eight years. To the best of my knowledge, Marathon has suffered no direct hits from hurricanes since well into the last century (1938 or thereabouts). Your idea is done by several we know. We had a power boat, but others keep two sailboats for the same purpose. We kept the boat on a rack and had it splashed just before we arrived and we would go to one of the local marinas, usually Faro Blanco, but we have used others on occasion.The boat we had was a Bayliner 2452. It slept two comfortably, had an enclosed head and basic food prep facilities. The boat just becomes a hotel roof after a few years. We bought this one for diving and other water sports.Jim