Burnt Store marina, east side of Charlotte harbor. nice folks, stayed a week last Jan in our 47' lagoon. lots of cat sized slips. short drive to punta gorda. enterprise rental car picks you up for free.
My bad it's called caloosa island marina it's on Marco but very safe, nice people and probably the best price wet slips for liveaboards in FL. http://calusaislandmarina.com/