For clarity, this thread is strictly about flying at high ASL elevations while staying within the AGL requirements. Any flight at greater than 400 AGL, with a few exceptions around and above tall structures, is an obvious FAA violation. 10,000 feet AGL is grossly negligent, and also requires circumventing DJI's max altitude above the launch point of 500m (or 1000m if more than 50km from the nearest airport), solely designed for mountain climbing from the base while staying within 400 feet AGL.
Had the opportunity to visit Bolivia mid year, launched and flew around +16 k feet on some peaks. Clear sunny skies, practically no winds, temperatures around 32-35 F°, had no issues whatsoever during flights, besides motors doing extra rpms. Remember cold temperature might affect stored batteries capacity, so avoid having extra batteries out in the cold open.
And be 110% mindful of your surroundings, don't go crashing your bird into a rock like I did. Cheers