That sounds really good and well thought out. I had a similar idea regarding a Tropical Island, so very happy to up-vote this one. A couple of the ideas I had that could go along with it (not sure if any of these have been recommended elsewhere so I apologize if they have):
-Geysers that would randomly erupt and have a spray radius around them or could be wind dependent (random couple tiles).
-Tide pools within the island that spawn clams, fish, and crabbits.
-A new tropical predator that is a combination of big cats like a Tigard (Tiger/Leopard) or a Liotah (Lion/Cheetah). They would be very hard to hear and quite fast (lots of movement), but perhaps scared off relatively easy (for a couple of days).
-Also played with the idea of rising tides onto sandy beaches every few days, but wasn't sure how easy that would be to do.
Thank you for putting this great idea into words.