Welcome Robert!
Blocking wind will help keep any humidity you create stay near the orchids. Either planting tall plants with dense foliage around the orchids, or draping fabric or building a fence to block wind might help. I'm guessing that partial shade from nearby tall plants will help the orchids survive the heat.
If you have plants, they will release humidity into the air from their leaves, requiring you to supply water to their roots! Drip bottles can prolong the availability of water to their roots.
You might arrange a large bottle or jug above the orchids, and make a tiny hole so that water drips from the jug onto the orchids, or their roots, or bark around the orchids, or some fabric tied to a branch near the orchids or screening tied around them.
If the hole is small enough and the bottle large enough, it might last for most of those 7 hours. of course, if you can refill it during the hot part of the day, you can let it drip faster.
GOOD LUCK!
(I was just about to ask drdawg to join the discussion, but I see we would have cross-posted.)
