[CPAP] Backpacking with a travel CPAP & using a CPAP over 8,000 ft

[OMyMyOHellYes]

Another thought:  8,000 foot elevation is nothing for the CPAP.  It just don't care. Like a honey badger.

It doesn't have to get to a pressure of say 15 CM H2O above sea level pressure, just 15 CM H2O above the pressure up there.  Remember, that much won't even start to blow up a balloon.  The machine just doesn't care. It's all differential pressure, not absolute.

Can you use the machine in a commercial airliner if you have battery?  Guess what?  You're using it at 8,000 feet right there.  Because on all but the very newest design airliners, that is what the cabin pressure is at while at cruising altitudes between FL290 and FL 410.  And even the newest ones have cabin pressures of 6,000 feet.

So....  I wouldn't give it a second thought.  YMMV. You become a test pilot at that point. Keep in mind, for medical equipment, the design "limits" are not the limits under which they will work.  They were the limits to which they were tested in the regulatory approval process.