S-Lancaster, I would assume that you could surely handle the driving challenges in the DR with your background. A long term rental would be costly, though.
In your previous post you inquired about the mopeds, etc. The reason that other posters tried to dissuade you from going the moped route is personal safety. Those moped riders sort of remind me of the "running with the bulls in Pamplona, Spain".
Mopeds being the pedestrians of course; other traffic being the bulls.
We rented a car in the DR last April and thorougly enjoyed the experience. We logged 1,200 Km (800 miles) during the week without incident.
Swede