There are quite a few taxi services for the Chetumal-Corazol trip. I have found the following people to be very reliable, and helpful:
George and Ester Moralez
[email protected]Phone: 501-4222485
They will meet you at the bus terminal in Chetumal, take you through immigration and customs,then on to the airstrip at Corazol.
Their charge is U.S.$40 per trip.
You just need to select your bus trip to ensure that you arrive in Chetumal, say 1 1/2 hours before a Tropicair flight from Corazol to San Pedro(or where-ever) - you need this time for getting though the border and travelling to the airstrip. Check this time with George, though.