And Freedom For All
Venice is the exception to the rule, fortunately, altho'' Jeff''s general description of the use tax requirements applies to many of the East Coast states. And the marine police there do indeed have a rep among boaters.
When/if stopped for not displaying a ''registration'' sticker for your documented boat, the first legal issue is how long you have been in that state (as proven by fuel or berthing receipts, e.g.). If your presence exceeds the state limits and/or you are not registered (as a documented vessel) with any other state, probably the best posture is to simply prove identity (e.g. with passport), not offer residential address, and accept the citation. The fee is $65 last I heard, and you are most likely in violation of the law (no matter what you think of its legitimacy nor how poorly represented it is by the Cornpone Patrol). Once you leave Venice behind, this likely won''t surface again anywhere else in Florida.
Sailing ''around'' Venice between Ft. Myers and e.g. Sarasota or Tampa Bay is also a nice alternative...