While I am not positive, I don't believe Boas are native to the DR, so chances are the one CB saw was a pet which escaped or was let go when the owner decided it was too big. There is now a thriving wild population of boas and pythons in Florida for just that reason.
One thing not mentioned, but if the OP's mom is squeemish about all "creepy crawlies", the biggest obstacle to living in the DR may be the LIZARDS. They are small, harmless (in fact beneficial), and IMHO cute, but they are also EVERYWHERE, and I suspect someone with a reptile phobia may not be very comfortable.