Don't worry too much about restricting the flow a little. Your filter pressure will rise and your gpm will drop some (you'll also use a little less electricity) but what you get in return is "hang time". You need to get the water up as high as possible so the evaporative process will have the most effect. (mine goes up about 20-25 feet). I have 4 1/4" holes and am probably running about 65-70% of my water thru the evaporator. The shower head idea will work probably as well....what you'll trade off in vertical height you may well make up for in droplet size.

I'm not sure you get the most "bang for your buck" running at night. The relative humidity is VERY much higher at night so less evaporation is possible. I run mine daytime only. Yesterday was about 93 degrees and the pool got up to around 83. Today and tomorrow will be 100......I'll be happy if I can stay below 86.

You may do somewhat better in Illinois and the folks in the desert could probably cool down into the 70's if they chose.