I caught lots of bone fish on my own on the north end of the island. I was on an anniversary trip with my wife who does not fish so I only fished from 5 am to 7 am each morning. I did best on undeveloped parts of shoreline. There were 10 -12 inch bone fish right in front of our condo at Co Co Beach which i did not mess with . Most places are not good wading.
Globalflyfisher did a do it yourself trip on your end of the island years ago so you should be able to find it on their website
http://globalflyfisher.com/reports/belize2002/own.php