Hi,
Whenever you're doing research prior to 1850, the convential approach won't work because of lack of information on the Census records and the lack of Census records.
FamilySearch is a good alternative to finding older information. Go to
www.familysearch.orgClick on Catalog
Enter New York, Rockland
Search
and a list of possibilities are listed. I clicked on Biographies and there are a couple of books that have biographies of early settlers. Successful Searching!