Just a couple of questions for the OP....
Have you been to the DR before?
Are you renting a car?
Are you aware of the driving conditions in the DR?
Are you planning on driving to Sosua at night, partying, and then driving back to POP?
I think that if the answers are NO, YES, NO, YES, then it would be much better for you to hire a taxi, it will be worth the money you pay. Driving in the DR is insane if you are not used to it, travelling at night on the POP-Sosua highway can be a nightmare. Then you have to worry about parking, theft, etc. if you are going to be sitting in a club all night, and the rental car is sitting outside unattended and sticking out like a sore thumb!
If you want a stress-free vacation, my thoughts are hire a taxi, sit back and enjoy the sights, party all you want, and get back to your hotel safely.
Just a suggestion from my experiences. I lived there, had my own vehicle, and still never drove to Sosua at night!
Marlie