In the Hugh Milsom book "Infrared Photography A complete Workshop Guide ISBN 0 86343 373 1. In it he has a section called Workshop: On Location. There he has a scene which seems to fit reasonably closely to your question. It was hard bright sunshine albeit at about latitude 50( Brighton U.K.) and high summer but not tropical which is about latitude 22. None of his locations are in the tropics and I don't know what another 30 degrees of latitude does to light intensity. For what it is worth he suggests F11 at 1/125th with Kodak HIE. The two pictures he took include reflective metal and white paint and sea and sand.
It's a very good book for those who wish to use Infrared film
we shoot HIE all the time. The time/f-stop combo mentioned by Pentaxuser is what we use as well for a starting point. It's highly recommended that you bracket, even in half-stops, which can make a huge difference in the "look" of the image.
Laurie White ("Infrared Photography Handbook" - another good book) suggests f16 at 1/125 with a red#25. It compensates for the focus being a bit off. She also says to try setting the meter for 200. I've decent results with both. Some scenes won't work with those, so play and see what works for you. Bracketing is a good thing, like aj-images stated.