I wish I could tell you Dominican Republic, or the dutch antilles but unfortunately , there are many pilots already there , Haiti shares the same island with Dom republic ( la espaņola ) its a VERY poor cuntry and dangerous as well
but there are several companies in Port prince , they fly Let 410 , caravan and J31 , try to contact them , and if you are in the area , just pay them a visit , easy convalidation also with your UK licence in fact straight away .
good luck