Unofficial map of Wharton's Batsto MTB singletrack...
http://www.jorba.org/sites/default/files/JORBA_Wharton.pdf
New official map of all of Wharton...
http://www.njparksandforests.org/parks/maps/wharton_map_web_version.pdf
The new official map shows doubletrack routes to use when the mtb singletrack riding conditions are less then optimal. You can ride the perimeter of the PBT on doubletrack, w/ a stop at Jemima Mount, or maybe w/ a sidetrip up to Devious Mount, for a fun ride.
My favorite winter/spring singletrack-is-too-soft-to-ride route includes riding the Washington Turnpike to the ghost town of Washington and on to Godfrey Bridge, maybe with a side trip to Hawkins Bridge or Oswego Lake. (If you have ever rented a canoe from Micks, you'll recognize the area.)
A CX'er had emailed us earlier in the year, excited about the doubletrack he rode around Atsion and Hampton Furnace during the spring. So that comes recommended too.
The Wharton Forest doubletrack is mostly (with a few exceptions) all good and fun to ride in the winter and spring when the Batsto mtb singletrack conditions might not be optimal for riding. With a bit of planning and a good GPS, it would be easy to lay out a long fun day (LFD?)