I guess I've been doing that for the past 15 years here. Perhaps accidentally but nonetheless those that survived are the ones I've been hatching. With the exception of lots of shade and lots of water I havent done anything this year to help. I did try the ice thing a few years back but they didn't care for it. I have used sprinklers on the outside of coops before to help but that hasn't been necessary for the past few years.
We did the ice thing last summer and it was just WAY to much of a PITA. We hose them down once, in the late afternoon to cool them off with cold water when we fill all the waters. MY silkies have been the smartest of the bunch and learned from our pig to sit in the pool of water to get themselves wet on their own to cool off.
Our polish crested, have done the worst in this heat so far.