I'm wondering if this is the same guy who kept trying to hit us up on Ambergris Caye, mostly in 2012. He even told us he was collecting for a bicycle race in town and needed funds for bike parts for the kids. We told him we'd donate they day of the race if he told us where/when it was and it actually occurred. We went to the place at the time he said, and there was no one there. Needless to say, we were not surprised and relieved we hadn't donated in advance.
Tall guy with a notebook, and usually (but not always) traveling (on foot) with a child.