New York, New Jersey, and Pennsylvania
.
Island Beach State Park - Cattus Island Park Downwind, photo from video
Marine
There are a number of sites here that are primarily for sea kayakers or other types of paddling, but they are potential sources of information about places to paddle and possibly can tell you if any of their members are also surfskiers.
Marine
Freshwater
Plenty of rivers with boats some of which generate surfable wakes. Sternwheeler wake riding (facebook video) somewhere near Pittsburgh?