Just remember Density Altitude and Steve Fossett. He hit the side of a rather high hill in a Super Decathalon in the same area.
I'm, no expert of flying in mountains in a light single but the fact that you ask the question shows good awareness of the issues.
I am sure that you will get lots of advice on this thread. All I can say is good luck, plan carefully and watch the weather. I am sure it will be a lot of fun.
MB