Plenty of shade, lots of grass and weeds, and a shelter that's in total shade so the sun can't shine on it making it an oven. I also have drip pipe with micro-sprinkler emitters punched in every 5' or so, and it hangs on T-posts about 5' off the ground. When it gets REAL hot here I turn that on and it puts a very fine spray of water over the enclosure.
I would just emphasize the effectiveness of watering/spraying the tortoises enclosure. On the 110+degree days I spray things down twice a day in addition to bubblers on an automatic timer that turn on a couple of times each day, in addition to being more vigilant about refreshing their drinking water dishes. Besides that, shade shade shade is critical.
They will need some sort of a heated hide box for the winter months.