Not MNNSHP, but a couple of years ago we planned on eating at CHH before MVMCP and when we went over they had closed at 5:00 pm. I assume the same on MNSSHP nights.
I can tell you that at MNSSHP 2 years ago, CHH was closed during the party. I'm not sure if that means they closed right when the party started or before. They were using it as a pickup spot for the candy, that might have had something to do with it.