Bone stock no towing. It was 80mph at about 3k rpm wouldn't go any faster. It stayed at 3/4 and as soon as I reached the top and dropped rpms it cooled right down.
Little hot but didn't seem abnormal. My 2018 Jeep SRT did the same thing holding high rpms up the same hill.
Weird gauge on this...
I had the coolant reading 250 going up a highway in AZ here around 90 degrees AC on. The gauge actually jumped to about 3/4 of the way. I think it was 230-250 the gauge moved finally