I love this idea. I must admit to having a similar idea myself for Santo Domingo, I wanted to get the homeless people to pick up trash and swap the bags of trash for a free meal or a bed for the night. Please can I suggest that you contact the Fathom cruise line, they are calling at Amber Cove 3 days a week from April / May onwards, and they have about 1000 volunteers who are interested in helping with community projects. Maybe you could get the volunteers and your community people to work together to clean up a particularly nasty area. That way you will get some meaningful work for the volunteers to do, and can get some additional helping hands with no additional cost.
But Amber Cove is about five hours from Las Terrenes.
Der Fish