There's an easy way to avoid that East Texas heat and humidity in a RTT:
1. Close the tent
2. Drive the vehicle to Colorado
3. Raise the tent and camp comfortably.
You're welcome.
This ^^^^
Back when we had our teardrop camper (which had no AC) we went on a camping trip to SE Oklahoma (Beavers Bend State Park near the TX/AR state lines) and camped with a group of locals, most of them were out of OKC, Dallas/Ft Worth or Tulsa.
This was in early April so the weather was fairly pleasant. The first thing I noticed was that every camper there except ours had AC.
When I asked about it, the folks there said "around here, if you don't have AC, you don't camp in the Summer, period."
When we went on a long trip to Yosemite and Sequoia later that year, we passed through Vegas on our way to Yosemite. We didn't even consider camping, instead we opted for a hotel. It was ~115f when we arrived. Our camper would have been a miserable sauna.