Sanibel has an ordinance prohibiting leaving it on the beach.
The only legal launching I'm aware of is at Punta Rassa, just before the bridge on the way to Sanibel.
I just bought a Wharram designed "Tiki 21", it may not be fast enough to suite you, but I really enjoy mine. Just completed a cruise from Cape Coral across Florida Bay to Tavernier for NAMSA Mid-Winters, then back home.
Lot me know when you're in town, maybe we can daysail