I know of Vermonster 4X4 in Bradford, Vermont. September 26-27-28. About 13 miles off the trail, RT. 25C Lake Tarleton Road into town. Always a heck of a time! They also have an event May 3-4 for all you early birds or sobo's.
Wondering if there's any more within 15 or so miles of the trail?
And if your into things like this along the way through Maine there's a few but not within 15 miles i don't think.