G'Day VF!
I'm not certain whether or not you've covered my question earlier in this most excellent thread, but I wonder if your Aussie physiognomy, originally unused to extreme altitude, had a period of adjustment as you began initial operations in the "roof of the World"? Did you encounter episodes of hypoxia, acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), or high altitude cerebral edema (HACE)? How long did it take you to acclimatize? Do any of your tourist clientele from sea level locales experience medical difficulties? Do you and your passengers use supplemental oxygen? I know that when I visited Denver, Colorado (a great town BTW!), a lowly 5,200' MSL, I had epistaxis (bloody nose) and dyspnea (trouble breathing). I am certain that my pack-a-day cowboy killer (Marlboro red) habit didn't help. That you are a yoga practitioner probably helped you. As a side note, I am given to believe that Nepalese Sherpas are genetically gifted with larger lung capacity and higher hematocrit (O2-carrying red blood cell volume) than we mere mortals...
Downward Dog and Upward Collective, Steve!
Good on you and those you love!
- Ed