Captain Jack Carlson who owns Two Conchs charters is the best down there. He doesn’t specialize in fly fishing, but can do it for reef and wreck fishing. He doesn’t do flats fishing though. If you want bonefish and permit on the flats try to find a guide in the lower keys, Marathon or Big Pine area. Less crowded flats then elsewhere. All the guides I have fished with down there are now retired, but there are lots to choose from. Maybe call a tackle shop for references.