Still a bit more exploring, this time to a spot I've never been to.  Fuller and Welsh Roads in Hartland, supposedly around a gravel pit and nearby to Lost Acre Falls (which I didn't try to find).

Unplowed forest roads within a portion of Tunxis State Forest, as well as some old woods roads.

Found my way through on the connections, left a few for "next time", and completed 5-miles.