I'm not ready to rule that Burrows Island, Cape St George or Round Island yet.
The last two have had an organization. I just haven't been able to get in contact with anyone yet and all the web sources have not been updated for at least a year.
The Florida Lighthouse Association page takes you to the same sources for Cape St George that I have already investigated.
Doc John is correct there is an organization for Sankaty. I'm going to try and get some updated info from them tomorrow.
As for Sharps Island- I'll start investigating that one and get back to you ASAP.
Dennis