Rob wrote:

I got through between Albuquerque and Santa Fe just fine in a Cessna
150 a couple of summers ago. Go early in the morning and keep a close
eye on density altitude as it relates to terrain elevation, airplane's
service ceiling, and your desired/required height above terrain.

One thing is climbing as high as possible outside the mountains and then
crossing them at high altitude in straight and level flight. No special
training required, anybody can do this.

"Real" mountain flying, i.e. flying in the valleys, is a completely
different beast, but wonderful and worth the effort.

Stefan