You might consider the 3 day sailing/camping/snorkeling trip down the reef from Caye Caulker to Placencia. It's a good adventure if you have any Boy Scout blood left in you! It's a good bargain for ~$250us/person.
Everything is furnished, meals, snorkeling gear,"lodging".
It's with Raggamuffin tours in Caye Caulker.
Can't remember the link but they are on the web.