When I (Eric) was about 6 or 7 years old, we went to Florida from Illinois. On the way back we stopped in Lafayette, Indiana where my brothers were born. This being in mid 70's with no seat belt laws, we just folded down the rear seat and the 3 of us laid on some sleeping bags.
We had to get ice for the cooler frequently, we traveled "cash only" or with traveler's checks. If the station wagon had AC I don't remember ever using it.