We share your pain. Driving in the summer in heat and humidity is tough. Not just air temp, but road temp (check your tire temps on those 95 degree days), and humidity factor into the equation. You are driving a big box (aka heat sink) in the sun on hot pavement. As long as you can cool it down in the shade you may need to take additional "cooling stops" along the way. Yes, there will be air leakage as RV's are not sealed, but I believe your biggest problem is cooling capacity diminishes as heat and humidity increase.
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