How hot is it really in the summer. Arizona/New Mexico

Ariz heat in the summer is unbearable and unpleasant even in an RV Park with full hookups. Driving during the day is also hard on your RV vehicle or truck. Suggestion, try a northern route and enjoy the trip. If you are set on driving the southern route, I would only drive at night or real early morning which I think kinda of defeats the purpose of the RV trip. Do a through check and maintenance of all your vehicles systems:)