You can probably cover most bonefishing situations with a 7wt. However if you are going to the Keys then a 9wt is a better choice. The only place I have been to where a 9wt. is total overkill is Mexico where the bones are very small. I understand Belise is similar.
Be very carefull if your 7wt. has a wooden reel seat and nickle silver fittings.
You must make sure that you do not get a lot of saltwater on the reel seat. Or rinse it off regularly with fresh water.
The fittings will rust very quickly and the wood is liable to swell up and rot.
I have been there and done that and now only use aluminium or titanium reel seats.