Our Mh did get warm and depowered on the eastward trip from Kingman to Flagstaff.
It doesn't seem steep but it is a long grade.
We stopped at the KOA in Flagstaff, and washed out the radiator, with permission. They have to haul in all their water.
When we got it home it was cleaned good. There are some grades in Az and Colorado and California that will tax a car even. that long eastward grade on I70 got our 95 Thunderbird hot enough we pulled of and let it cool down, while running. There is a grade here that Truckers make a joke about it being called a mountain but in the last two months there have been several runoffs into the safety chutes by Truckers and one went through a concrete barrier and down the side of the mountain.