There was something I picked up at bass pro awhile back for duck season here in S. FL. I believe it's called a frogz towel. They were like 6 bucks on sale. You soak them in water and they retain it. So you're not dripping water all over you but it helps to keep you cool and retains the moisture. Really helped me out. Think of it as a giant wetnap that never loses its cooling factor and moisture. Works for hours before you need to soak it again.
If you've got one foot in yesterday, and the other in tomorrow, than you're pissing on today.