Paul Menta checked out some spots in Jamaica a few years back. You might get in touch with him through
http://thekitehouse.com/ . I was wondering if they have trade-thermal wind interaction along the north coast like in Hispanola. Apparently they do to some degree. Also, even though Kingston is on the south coast, I understand they have winds periodically as well. You can find some wind records at:
http://www.wunderground.com/
I had the same thought about Cuba. Folks from the USA are still technically barred from traveling there though. I understand there are quite a few good launch areas and few kiters at this point.
Unfortunately, September seems to be a marginal month for wind in much of the Caribbean. Even the ABC island latitudes become uneven. I am not sure what to recommend in the area for solid wind prospects.
That is except for tropical weather systems including hurricanes. September is prime time for storms. Not real reliable or safe either for that matter.