Don't know if this might help. I recently purchased a sailboat in the Tampa area. It was reportedly a local livaboard and cruiser for many years before I purchased it. It was reported to me that it had a livaboard slip in Cortez.
I got the vessel from a brokerage slip in Palmetto so I can't pinpoint the marina. But I do have another sugesstion. Call Todd Delaney, you will find him in the local directory under Marine Survey's. If you cant locate his number call Sneed Island boatyard and they will have his phone #. He is pretty plugged in to the local boating scene, and is in my mind a pretty comprehensive marine surveyor. You may need his professional services and advise when they find a vessel, but for now, he will know what marinas are accepting livaboards.