Hello Leslie LaPlace,
Did you try FitnessConnect? I am sure you already did an internet search; but, here is what I found that may help you get started. I would also try contacting the gyms and certifying agencies/education centers to find someone. Good luck and enjoy speaking with others.
Natalie aka NAPS 2 B Fit.
I cannot give you a reference. But the Dominican Republic is a very affluent country. Your client will have no problem finding a trainer there. I traveled the carribean years ago and DR was quite posh. The other half of the island is Haiti, which is the opposite, empovershed and still recovering from terrible storm damage years ago.