Just remember if your in the mountains above 6000ft, your already going to have to double your water intake from 2.5 qts a day to about 4qts b/c of cold weather and altitude without any supps. On top of that be weary of Acute mountain sickness (AMS), HAPE and HACE.
I would suggest acclimatizing first before starting. Creatine will impact your water intake and then anavar will as well. Dont want to rain on your parade but you need to be in shape before you hit the mountains, you cant do it while running around at high altitude. Its too dangerous to go there thinking you will get in shape while there. You have the altitude, the combat operations and i would look into what it may do to your blood. Will you bleed more while on anavar compared to not being on Anavar? If so what if you get shot and your high up where you need CASEVAC with the SKED and ropes. I only bring these questions to mind because i am Army Mountain Warfare Qualified and know the mountains kill, its only a matter of time. I would do research and ask around about the anavar and the science first. Its already dangerous there, do you want to make it even more risky by taking a supp that could cause problems to your body at high altitude. The oxygen content is thinner.
"Mobility is lethality" Ascend to Victory