I believe skirmishes will keep going tout until midnight assuming the weather is OK (and it’s not completely picth black and really wet and slippery), which also means the hospital will probably have things to do until the last of those is back.
Plenty of places to sing - just follow the noise, drinking not obligatory. I sang until 1am both nights last event, once round someone’s fire which was fairly rowdy, and then in a tent which moved most of those participating to tears. The Navarri always welcome more faces to theirs.
Conclave meetings can occur later, I know one of the scheduled herald appearances was 11pm last summit.
There’s more than one casino.
You can join the dancing class in the senate (11pm I think).
And I’m completely teetotal.