It is fairly easy to get in high 70s anyway. You can either close off your bunks. (Which I do not because I like my sleeping area cool). Or you can get a custom made bunk cover at
popup gizmos They can be ordered right on the website. They have a flowchart with thousands of popups listed. Choose your PUP and model. Spend that money.
No I do not have them. The places we go usually has plenty of shade. and even last summer on our 115 degree days. My A/C kept our PUP down to mid 80s in heat of afternoon, down to low 70s after sundown.
I did go inside a PUP that day (that had the bunk covers) and his was at least 5 degrees cooler.