In my opinion access to water, shade and airflow are the most important things. Sounds like you've got the shade part covered. My neighbors cut down a huge tree that was a good part of my flock's shade. I had to add a generous, double layer shade cloth overhang but that did the trick.
Second thing I do for them is have fans supplementing the airflow in the run. My run is about 8' x 14'. I have one box fan on a short side and two on one of the long sides so that there's a strong air current they can choose to expose themselves to or avoid.
When it goes much above the triple digits I bring in 5# blocks of ice. Five pounds can hold up fairly well through the worst part of the day here in SoCal. Fortunately, when the sun goes down our temps drop very quickly.
If I were smarter I would have chosen heat resistant breeds. Prob is, now that I know that's what I should be doing, I still don't care for how they look. I'm struggling with that.
