Like many, I have lived in the west most of my life and remember as a kid going over the dreaded GRAPEVINE on a family trip from Los Angeles to San Francisco. At that time the family was Mom, Dad, Grandmother Hewitt, two older brothers and an older sister. There were seven of us in a 1936 Chevy Deluxe, four door sedan. We didn't stop until we got to Bakersfield and needed gas. The war had just ended and we no longer needed to use Ration Stamps otherwise we couldn't have made the trip.
Back to the subject. Dad and one of us boys, bled the brakes every month or two and among other things Dad was a mechanic. The coast route was not considered as a viable route and there wasn't any interstate system so the Grapevine was it. No overheating and no smoking or hot brakes, Dad just drove it at a safe speed and one that wouldn't burn up brake shoes or damage those hand poured babbit bearings.
We just drove over Wolf Creek Pass in So. Colo. last month in our signature rig, no biggy. Used pull outs when needed for others to pass and stopped to downshift to low in one spot about a quarter mile long. NO! hot engine and NO! hot brakes.
Worry about the the hills and mountains is not good for your mind and body or your pleasure in seeing a huge area of this country.
Like some ad guy said for Nike, "Just Do It".