I just found your previous post which pretty much answers my question.
For us, the extra light at the back of our TT afforded by opening the rear door is a bonus, but we too do not want the A/C the entire state park.
Having said that, a 'controlled burn' close to the campsite made opening the doors impractical even with our A/C off, your plex door may have been the answer.
2015 Toyota Tundra Dbl Cab 5.7 V8
2017 Zinger Z-1 291RL "Harvey'