Thanks for writing in with your questions. Thanks for the kind words.
Yes, you do need to adjust your HR zones for altitude or you will be training too hard. I work with a number of CO athletes who live around 5500ft but train at 8500+ft regularly. I recommend doing the HR drift test to determine your 8500ft AeT (top of Z2) and doing a 8500 time trial of 30-45min duration to find your altitude AnT (top of Z3). While the gas exchange test is a good idea if you are training at 5500ft it is not going to help you in when you are at 8500 and I do not know of a standard correction factor you could apply to the 5500ft test.