I've heard there are some primitive campsites near Colgate Lake. Not sure if this is true or not, also nor sure what the road is like up there right now. But it might be a possibility worth looking into.
This is some more information of the informal primitive campsite near Colgate Lake. It is at the first of three parking areas along County Route 78 east from East Jewett (shown on NYNJTC map #41). It is approximately at the cross hair on this topozone map. I have never camped there, but I have seen tents of hunters and car campers many times. There is a port-a-john north of the road at the 2nd parking area (near the Colgate Lake dam). I don't know if the port-a-john stays all winter. Also at the trailhead here, 3rd parking area, there is a large meadow where it should be possible to camp. I suspect the trailhead parking area is the most likely to be well plowed in winter. This area is south of the Blackhead Range and north of Tannersville.
The standard DEC camping rules in the Catskills would apply: Camping is permitted on state owned land, more than 150 feet from any structure, water source, stream, lake, road or trail.