Living in the DR is hard, petty crime is a way of life. Unfortunately it has only become worse in the past 10 years with all of the inflation and increased poverty. The middle class has pretty much disappeared. Believe it or not there was a pretty large middle class 15 years ago.
Anyways, here is how my family keeps our house locked down:
Bars on every single window, AND barred doors. If you have a home, build a VERY HIGH WALL. I'm not talking the pathetic 6 foot walls, I mean 15 foot walls. Place something sharp on the top of the walls, if you want to go cheap the old dominican way is broken bottle shards. The walls are so high you can't see it anyways. Or you could put barbed wire embedded in the cement.
If you live near another home, make sure your walls aren't accessible from the other home. Having 15 foot walls do nothing if a burglar can access that wall from the ceiling of a neighboring home. In that case, build the wall even higher on that side.
A dog is a must, preferably more than one. Also, if you have a 2 story home, ensure you have a solid, steel or wood door at the top of the stairs blocking access to the second floor from the downstairs portion of the home. This door should also have a strong metal gate. Security systems are also useful, with very loud alarms. Floodlights outside you can turn on from your bedroom is also a must.
Really, nothing is going overboard in the DR. However, you need to realize if you are an obvious foreigner living in a poor area you WILL be targeted regardless of the amount of security you possess. For those of you who live in a high rise in Santo Domingo, it is also CRUCIAL you have bars on your patio glass doors. Too often people overlook this purely due to being on the 4th floor or higher. Patio doors are very simple to break into.
Hope this helps. Oh yes, I personally hate guns but BUY ONE! Make sure everyone knows you carry it. Keep it outside of your belt buckle, the locals will notice. If there is a shooting range, go shoot a lot. It's actually quite fun. Shoot little guns, big guns...........talk to people. Be that crazy NRA american they know will shoot them in a second.