If you look on line for some of the patio mister systems you can find heads that are as low as .006 gpm or .36 gph. I used the kit for livestock, can't tell you what brand it was, I did have problems with the heads but not from debris the kit comes with a filter, my problem was more from hard water. I would have to soak the heads in vinegar at the end of each season. HomeDepot sells the stuff only it is seasonal. I found heads that were directional helped get them aimed for coverage.
We did take a cooler, plumed it with copper tubing, left all the extra coils in the cooler and filled with ice and water each morning, trying to get even more cooling from the misters.
We also had a swamp cooler running on them, picked it up on Craigs List. Built a stand for it so it was at the right level.