The roads are good to Enriquillo Lake for the most part. You can perfectly rent a car. You must mean Pedernales (in the southwest). I wouldn't suggest you stay in the North if you are headed to Enriquillo and Pedernales, as you will be about a seven-hour's drive away. If you must go both southwest and to the north coast, plan on overnighting in Santo Domingo. It's three hours to Enriquillo Lake, another almost 2 hours to Pedernales. And it's three hours to Puerto Plata from Santo Domingo (not taking into account time for getting lost). Santo Domingo is the intermediate point that you have to connect through either to go west or north.
Prior to making your plans, I suggest you check a map of the DR to get your bearings and to choose your airport of entrance and departure wisely. If you are heading southwest, you will want to land at the Las Americas International Airport (Santo Domingo). American Airlines may allow you to enter by Santo Domingo and depart by Puerto Plata (Gregorio Luperon Airport) that is north as they have flights out of both destinations.
