I am using 50% shade cloth. It immediately lowers temperature and diffuses the intense light so the plants spread a little more as opposed to just reaching towards the sky. I have the cloth positioned so direct light strikes the plants until about 10:30 am, then diffused until 5 pm and very late day direct sun again until darkness.
I have one of the valves/irrigation lines run down the top/center/inside. I will add misting nozzles to that line. That will cool the interior. The valve system allows me to program each line to run up to twelve cycles a day.
With the circular drip emitters, water only has to be run for four minutes at a time before there is any run-off. That water is allowed to run onto the dirt floor.
I have the pots on plant elevators so the pot is not in contact with the ground (gopher control and helps temp). When the hardcore heat of June arrives, I will put the elevators in trays/saucers surrounded by pea gravel so any run-off collects and then evaporates around the container, creating a tiny micro-climate and aiding in keeping root temp down.
Our water has been tested and other than extra calcium, is excellent and PH is near perfect out of the tap. I am very fortunate in that regard.
I’ve only been growing for a few years outside so I am far from an expert, but got a successful harvest each time (with many “learning experiences” along the way). If you live in/are visiting the Tucson area, you are welcomed to come have a look.