hmm - I thought no overnight use of Half Dome, last time I checked...
so all you gotta do is "we're taking some night photos" and you're still ok to spend the night up there? Or you have to get your butt down before midnight? Probably a matter of "who's gonna check?"
Main reason I have not been back to Half Dome in now over 20 years is the above sign. The last time I was up there we did spend the night, almost alone.