A very wise decision to start such a tour very early in the morning, I can't imagine the high temperatures that are reached during the day in such a location.
The images are fantastic, almost apocalyptic and although it must be much more amazing to see it in person, reading your comments about the immensity and distance is amazing to me.
I agree that it must be a marvel to enjoy the walk accompanied by that scale of colors. It's said that's why the desert is deceiving, that we think about the heat and forget that at a certain altitude we will always be more susceptible to the cold hehe.