and with a sense of humor ta boot... lol
If it were me I would kinda want something private. A couple of suggestions come to mind...
You can hire a boat to take you to one of the remote Cayes and have a beach BBQ, OR have a restaurant prepare a meal for you at the end of a dock with wine, linen, candles, and all.
Ya know, Caribe Island Resort also has a Palapa in front of their resort I'm sure they could take the hammocks down and prepare a lovely dinner for you there right on the beach, or out on their dock as well.
Otherwise maybe a romantic boat ride to Capricorns (North of the cut) and let them handle everything as well.
She is a lucky gal, ya sure sound romantic to me! (except for the last comment)
Let us know what you decide...