Some other things I tried last Sunday that I didn't mention. I found these wristbands on TW, I forget who makes them, but they're described as a towell for your arm. They're much bigger than even a double wristband and kind of expensive, but I like them. Switching to tournagrip helped incredibly with sweat absorption. I was using a white overgrip from Gamma which is a little tacky. Great for fall and spring, but not summer.
I also read about how polyester has basically no breathable qualities to it so I decided to ditch the poly and try cotton. I wore a white charged cotton t shirt by UA for that match and I think that helped a little.