I know of none on Ambergris Caye, there are some on the mainland..
Here are a few places to camp, and some other lodges and hotels not listed here often will allow campers to pitch a tent on their grounds, and of course that's also the case with private landowners (though there could be a safety factor):
Lagoon Campground, north of Corozal Town near the border (also set up for RVs, about the nicest little RV place in the country)
Caribbean Campground, in Corozal Town
The Trek Stop, near San Ignacio, Cayo
Jungle Drift Lodge, Bermudian Landing
Cosmos, San Ignacio
Chaa Creek, San Ignacio (has "safari tents" set up)
Mountain Equestrian Trails, Pine Ridge
Clive's Campground, Placencia
Following are some of the reserve/park areas with some type or another of "official" camping. At some of the other parks and archeological sites (Altun Ha, for example) camping is permitted but with prior permission.
Cockscomb Preserve, Stann Creek
Community Baboon Sanctuary
Five Blues Lake, near Belmopan
Bocatura Bank, on the Sittee River
Douglas De Silva in the Pine Ridge
Thanks to Lan Sluder of Belize First for this camping information.
[This message has been edited by Marty (edited 06-26-2000).]