It's a gonna be hot. Halfway down this Webpage, just below the Radar Map, see 'History and Almanac'. Plug in some dates, and prior years, to see how hot it's been historically. Then, look at few dates -/+ your travel week. This will give you a more accurate overview in case a single date historically was not representative. The 110 F mentioned above is pretty accurate. You can also put in different Towns along your Route, of course. I put in Phoenix because it's close. The fact it has a major Airport means it posted very accurate Weather Info for Pilots over the years.
Meanwhile, the ~R-5 or R-8 Insulation values in many RVs doesn't provide much protection against Heat ingress. So, A/C typically can't keep up.
Weather Underground
