Most of us, reading today's newspapers where they describe a 14 car pile up on the nation's largest highway--pure stupidity--will recommend that you hire a car and driver.
That is the old "leave the driving to them" attitude. And what it does, it allows you and your companion the opportunity to enjoy the scenery without fear of missing a turn off or a road sign.
IF you take that decision, then we can suggest some nice stops along the way, such as at T?pico Bonao for a beer and sandwich, or at Jacaranda for a Lechosa con Leche and a ham and cheese for less than $3.00....
If you look at a few threads about the challenges of driving in the DR (especially for newbies), I think you will consider the alternative....
HB