Boat shoes, sandals, or Flip-Flops (your own) on the ground will give you the best information. A vacation visit to the area is a great way to look and have fun at the same time. We visited friends for ten days and went home with a house contract in our luggage.
RE: water clarity. The rivers (Peace, Myakka, Caloosahatchee) all send fresh water containing tannins? into the Gulf or the Harbor. Brown color may be evident from that. Lower Charlotte Harbor and out into the Gulf is clearer, but seldom pristine. Charlotte Harbor sailing is pretty protected and not much activity like para-sail boats or Go Fast Boats. Plenty of sailing clubs as mentioned for cruising and racing activities.
A Craigslist search for property for sale in those areas may be a reasonable beginning of a serious search from afar. Contacting a realtor with your interests will probably get you information on homes that could be 50% to 100%+ above your target price
(not that there is anything wrong with that). Some Realtors may offer a buyers search agreement in which they would look very specifically for the property you describe and send you the pertinent information.
Contact an insurance agency too. Insurance costs vary greatly depending on how low to the sea level your house is located. Rumblings of large jumps in those costs are afoot. Taxes and Insurance are costs to include in the equation.
All that being said, this area is a great place to spend the winter. We day-sail about 3 days per week. We drive to a rented dock in an owner's backyard. Many waterfront owners are willing to offer dock space and defray their own costs. Marinas in the area have more facilities than the backyard dock, but they are more expensive too.
Enjoy the adventure.
