Turns out I'm an idiot and only NOW learned that you can make polls! Vote for whichever day you'd like to have the party. Vote for both if you're planning on going and don't care what day it is.
However, now that I'm typing this I think I might host it on Dec 2nd and have Dec 9 as a backup in case of crazy rain like last time!
Oh well, vote anyway and I'll use that to inform my decision!