Hi Paula
In addition to Paige’s advice you may want to check to see if you can rent oxygen. I live in Carbondale and our house is at 7200ft I too have long-covid and due to the damage to my lungs I am attached to oxygen most of the time I do have my own concentrator at home and have a portable one. There is a supplier called Aerocare and they will deliver I used them after my release from hospital and they were very responsive. You may not need this service however it might give you comfort to know it is available should you need it. My COVID occurred 22months ago and I was in hospital 75days I have been spending a lot of time in Arizona at lower elevation and do not need the oxygen supplement but as soon as I get home I am back on it. My intent is not to alarm you rather to let you know that oxygen service is available.
Enjoy your trip
Trish