I just want to say that a good friend of mine was taken by ALAMO rentals....he had a tree limb fall on his vehicle as he drove over the Tourist Highway going to Sosúa. Messed up the windscreen and roof line big time. he HAD taken out insurance. BUT they told him that the damages were not covered since he did not have the "glass" insurance....Took $600 of his hard earned dollars...His Canadian Credit Card Co. only insured him in Canada!!
Just in case.
Heck, you can get to those places by gua-gua! And it would be a real fun experience....ask one of the local folks at your hotel to show you how to do it. DIRT cheap!....
Good luck,
HB