..........If you ask me (and no-one did) having to pay a few hundred dollars to register your already documented vessel, just to pass through Florida waters, is (choose your adjective).
"Don't take life too seriously - Nobody gets out alive"
You may wish to review the Florida regulations. The state is not requiring you to register your "already documented" vessel, or a vessel undocumented, but registered in another state when passing through Florida. Three months is allowed and then, in addition, there is very little monitoring. Take care and joy, Aythya crew