You probably will not need air conditioning for your trip. :)
Also, I would not recommend making reservations for your whole stay unless you want to do it a day or two beforehand. There are plenty of places to stay and if it's just an overnight, there are some gorgeous boondocking spots. You can be a lot more flexible without reservations. Suppose you don't like the area or like it so much you want to stay longer. Suppose you have mechanical problems or there are road problems. We find it very easy to travel without reservations. The only ones we made were for July 4 weekend in Palmer, Alaska and 5 nights in Denali's Teklanika campground. We made those about 3 weeks prior when we had a better idea of when we'd be there.
Have a good trip!