Yeah.... you'll piss out more if you drink more water....
but you won't be as dry as you would if you drank less.
Also, my advice to Be There. On the day of the show, try to be awake for a longer period of time. As in, if the show starts at 6pm and you were going to wake up at 10am, wake up earlier. You should be more vascular and less bloated doing that. Oh and move around all day. Don't just sit on the couch.
And PTPP.