That seems heavy.

I wear an inexpensive evaporative cooling vest on the moto. I question whether it would be effective at the lower speeds of bicycling, but I know they sell them on bicycling websites. It's very light and lasts about an hour and a half at freeway speed. The greatest advantages of evaporative vests are the low cost and that they can be recharged in minutes simply by soaking them in water.

Sure, public restroom sinks can be disgusting, but it beats heat exhaustion, and you're only putting it on your torso, not in your mouth.