I am no expert on salt water fly fishing but I have fished with a fly rod for bonefish and tarpon in the Florida Keys a few times, and have fished in salt for redfish, trout, snook etc. for many years. In the Keys guides like a 9wt for bonefish, not that a 9wt is needed for the size of the flies or the size of the fish (although my understanding is Keys bones are larger than those in Belize), it is the constant wind that needs a heavy rod.
Most people recommend an 8wt for bonefish and that would be what I would suggest. If you can swing two rods my next suggestion would be a 11wt. With an 11 you can handle tarpon plus it is not greatly oversized for permit, large jack, etc.
Now for reels. Saltwater is very hard on reels. As 1minute said above you must flush the reel (and rod for that matter) after each use. A salt water reel with construction to hold up to a salt environment and have a drag suitable to handle bonefish and tarpon are expensive, I am talking $500 to $800 each according to size. This is much different than a fresh water reel which a good one can be had for $200 to $300. I would recommend Nautilus NV reels as a good quality saltwater safe reel.
