If you find it difficult to find a long term rental in the Florida Keys it's because folks make more money renting short term along with using it themselves.
If you need a long term rental and do not plan to buy call as many places as possible that rent in the Florida Keys.
If you see one you like in the listing link below send me an email. If I do not have it listed I will send you the contact information for the agent that can help you with that particular property.
Click the link above for MLS listings.