The following webpage has listing of campgrounds in Vermont
http://www.campvermont.com/
These webpages have summary listing of campground and give the opening and closing dates:
http://www.campvermont.com/html/cgs/...gamen_aj_f.htm
http://www.campvermont.com/html/cgs/...gamen_kz_f.htm
I've heard that Lake Dunmore Kampersville campground is good and they are open year round.
FYI: Vermont got snow last weekend.