That would probably be the safest bet, but you'd need to guarantee the room for late arrival with a credit card and make sure your arrival plans are known to avoid potential confusion. I usually call the hotel before midnight and let them know what time I'm getting there if it is going to be after midnight or else when they do their room audit they might think you're a no-show and clear your reservation, possibly giving your room away, and creating hassle at check-in re-creating your proper rate, etc.

You could also call the hotel directly and see if they can work out an early check-in for you. If they agreed to an early check-in and worse came to worse and something got mixed up, you could change in the gym, give your bags to the bellhops (who are sooooo helpful!!!) and then hit the pool/beach until your room is ready.

Have fun there! Its a really lovely place with friendly people.