I was once further up Allen Road, at Bartlett's Bridge where the Batona Trail crosses, and I saw maybe that same truck with one or two golf carts on it, slowly bumping its way up the road. I asked someone if there was a golf course in the forest (!), and was told that there is a gun club up there, and the carts were probably going there.
I don't know exactly when the Stage Road bridge re-opened. I'm pretty sure the detour signs were still up Monday morning. There was a Marathon/Triathlon this past weekend at Bass River State Forest, and just days before, they (the people who ran it) found out about the bridge closing and had to re-do their routes in a rush, including trying to get State DOT permission to ride on US-9. If in fact the bridge re-opened before the Triathlon, and their detour was not needed, I think they would be really annoyed...