Hi Holdown,
Great place you are heading for. Here are some ideas:
A sling will work a good bit better than a pole spear, at least for most people. It takes a little practice, but is deadly once you get used to it and has a lot more range than a pole spear. Most of the slings you buy are pretty worthless, try to get some 1/2 inch amber rubber and make your own. A 5 ft, 5/16th dia spear is right, not longer unless you are a gorilla or commercial lobstering. The 1/4 inch shafts fly real nice and are fine on small fish.
Is it overhunted? of course, compared to times past. Still, you should be able to get dinner in most places. Where will you be, Exuma? Where exactly? I spent a lot of time there a while back.
Technique: find the fish from the surface, go slow and smooth and get directly over them. Dive straight down, cock immediately and weight yourself so you don't move after you leave the surface. If it works right, hogs and grouper both will sit still and turn to look up at you as you come into sling range, makes for a good shot. If you come down at even a small angle away from vertical, it does not work nearly as well. For snapper, aspetto works better. If it is very deep or the vis is bad, covering a lot of ground 10-20 feet down is a good scouting technique.
Wetsuit, a shorty will feel real good. A 3/2 surfer full suit would be nice too, maybe a little warm for October.
Good luck and give us a report when you return.
Connor