Keep in mind that there are islands and there are islands. Size matters, as does distance from shore. Knew a woman who worked as a caretaker/house sitter on an island in Maine. It was about five acres, Rockport area (at least I was in Rockport when I met her) and only a hundred yards or so from the mainland, but with no bridge access. At low tide you could wade ashore, otherwise it was a boat. No ferry service here, but the owners, who lived in NYC or somewhere, had several boats and a small boat house.
The owners were only out to the house in summers, pretty much left before school started. She tended to their needs, some cooking and housework, and any maintenance she would schedule with the needed contractors. Bottom line was that she got free lodging and a small allowance, she worked as a writer and photographer (why we met), and had almost nothing to do on the island in the winter. No ice, it was salt water, but cold and somewhat wet and storms could keep you from taking the boat anywhere for several days. No internet back then, but power and phone came from cables to the mainland, so rare power outages might be the worst. Except for the isolation.
In the end, she was bored half the time and potentially suicidal the rest. She needed people and was planning on leaving as soon as she found somewhere else.
I have a friend who lives on an island in Florida, also no bridge but they have a small airport and he has a plane, as well as boat. About two dozen people live out there year round, and he works four days a week on the mainland. He simply flies over, takes his car out of the hanger he rents and puts his plane in, and goes off to work. He's single now, children have moved all over the country and his wife passed away a decade or so ago. He loves the semi-isolation, spends his off time fishing and puttering around the house. There is a ferry, and a ton of day visitors, so he has plenty of people to meet. He spent 20 years in the Navy long ago, sailing around on a destroyer, and he says the island is just a big destroyer for him.
So, pick the type of setting you need and then write it. For Maine, there are plenty of references, and a good reason for a week's research driving the coast and eating lobster.
Jeff
I also lived in Bahrain, which is a much smaller island, but a lot more tropical than you're after. (it is in fact not quite tropical AFAIK it's just a tad north of the Tropic of Cancer.)
