I was going to say, "If you use Moenkopi as your outfitter, Brady will give you all the good beta you need," buy you beat me to it, Brady.
I like Brady's idea of deflating a floor for peeing. This is a VERY important consideration, especially if you will be imbibing during dinner or during the float. What we did was lash one of the cargo nets securely between three of our boats. This created a a safe area for females to go cop a squat. One girl used it three times... I'm glad I didn't have to drive home with that one--pee breaks just kill your travel time!