SierraNevada: thanks for the aerial photo. I agree that a few extra cairns in that area would probably be useful.
But my main question is the part about “deadly cliff”. It seems like if you reached a place like that at night, it would make sense to turn around. In October 2013 on the Mountaineer’s Route, I missed a switchback in the dark, while hiking alone. Eventually I found myself on a very narrow ledge, with a long drop-off. So I made a U-turn, and found the correct route.