... a specific / limited power of attorney (poder especial/especifico). The power of attorney ought to be in Spanish as it will be shown thru all the paper trail, at the police and other authorities. Maybe it will even have to be notarized at your Dominican Consulate and again maybe also authenticated at the local (in the DR) fiscalia(?).
Selling to locals is difficult and can be a drag... it's usually not the lack of interest but the haggling with no finalization at the end.