I have visited Islamorda many many times. The fishing there is very different to the Bahamas.
With the exception of a few Ocean side flats, the flats are mud with a certain amount of grass on them. Very dangerous to wade.
The flies used are usually more brown coloured than typical Bahamas flies.
The best examples of these are Tim Borski's flies.
However if I had to choose one fly then it would be Harry Spear's Tasty Toad. It simulates a toad fish and also a sort of craby shrimpy thing. Look at Dick Brown's book for tying instructions.
I can assure you that is a fly used by many of the top guides around Islamorada.