Hi, I do know that some travel packages take you to hotels with private beaches and a number of them are nudist. Sosua is mostly top less and the bottom parts of those bathing suits are delicatly invisible. If you wish complete privacy right on the beach with total nudity, there's a beautiful hotel in Las Canas, about 40 minutes from Puerto Plata (to the east)which you will find very private.
The RD is my favorite place, I will be going there probably before year end.
Good luck and enjoy it. If you find something else, let me know.
Serge.