What model do you have? Where are you currently camping? What's the site like.. Full sun or some shade?
How are you covering the cab windows? Remember the cab area has sheet metal and glass for insulation. I can cook an egg and bacon taco for lunch off my dash in the summer (if not covered)
In our parts of Texas we are already seeing highs slightly above 90 degrees, which cool for this time of year due to all the rain. We were camping this weekend and I forgot to cover our cabs windows (spot was full sun no shade)... Came back to RV around 2pm and it was 78 degrees. That's about normal for us if we are in full sun. Put up the reflective foil windshield covers and cab curtain, next day had no problem keeping it around 75 degrees.
Once we get into full 95-100 degree heat we dream of 80 degree inside temps. Every RV I've owned couldn't keep up with Texas heat load if in full sun.
IMHO every RV over 26 feet should have two air conditioners.
2011 Sunseeker 3170DS - 30,000 miles explored