I made a quick trip to Delmarva Peninsula to see the distinctive subspecies of fox squirrel. The best place is apparently the southern side of the loop trail called Woodland Trail in Chincoteaque NWR. The squirrels are a bit shy and tend to freeze when you walk by, but I easily found 3 in 1 hour. The best time is about an hour after sunrise. There’s also a very obvious fox den close to the trail. At night there were a few foxes, raccoons, and deer; with a thermal scope I also found a white-footed mouse and a southern flying squirrel.
People coming from Philadelphia or New York can try to save a couple hours of driving by looking in Prime Hook NWR, where Delmarva fox squirrels were reintroduced in the 1980s. Try Pine Grove Trail. I only saw eastern grey squirrels there.