There are half dozen marinas, located deep inland on Okeechobee waterway.
While transiting the area last year I noticed reasonable storage prices there and it looks like the area is well protected from hurricanes...
quick googling found this article
BoatUS Cruising Logs
However, Florida is expensive and marinas are filled, if you go either north to North Carolina or west to Texas, you'll find more and more reasonable prices and more spaces to park a boat. Cruising USA waters is fun too