The constant question.....
IS A DOCUMENTED VESSEL EXEMPT FROM STATE JURISDICTION?
No, all documented vessels must comply with the laws of the state in which they are operated. The vessel's document must be shown to state law enforcement personnel upon their demand. States may require documented vessels to be registered (but not numbered) and to display state decals showing that they have complied with state requirements.
Quoted from the USCG Documentation Center Faq
Vessels in Florida for longer than 90 days must be registered with the state, but do not require you display their registration numbers but do require display a current registration decal.
See The USCG National Vessel Documentation Center
for additonal information on Federal Documention of your recreational vessel.