I've been to Santo Domingo like 5 times now and the only place that you can wakeboard is in Caberette at the Caberette wake school. I've emailed them several times ine the past month and i believe that all the instructors should be out there now...I also believe that they are runnin a SAN.
http://www.activecabarete.com/cabwake If you make it out let us know how it was.....I'll be there again soon and plan on doing a extended trip to head there