RE: Best truck for large 5th Wheel
Get a long bed dual wheel. Add an auxiliary fuel tank. You will not have to pull that large 5th wheel into a gas ststion. Get in for the night unhook then go fuel up.
RE: Cripple creek/Pikes Peak
Another mountain in the area to drive to the top is mount Evans.
This use to be the tallest paved road in the U. S. until they paved the upper half of pikes peak.