I took him on an antelope 2 years ago. We slept in tents while it was 13 degrees at night and 30 degrees during the day. He fared well then. However, the terrain was much easier and at a lower elevation. It's not like he did not know what he was getting into. I suspected this might happen based on his lack of cardio and time spent at the range.Congrats, sounds like a great trip. I'm looking for my first western hunt next year, my only concern is my hunting buddy being like yours.
Good luck to you S.Engineer!