Another update: "Truck NY 17C" has the same story as Truck NY 14. I did, however, find a Truck NY 96 in Candor along Mill Street and NY 96B. There are also "Truck To NY 23" signs on NY 12 NB approaching Norwich directing trucks to CR 32B and CR 32; I am unsure if this is something that counts, as I did not see any evidence on NY 12 that this is any different from the "Truck US 9/NY 50 south" situation in Saratoga Springs, but I didn't poke around too much either (downside of finding it at the end of a trip), and there isn't current street view there.