Might as well keep this thread going-
I just got back from the north. It is possible to get air fills in Yellowknife. I got my air fills from Fire Prevention Services. Small compressor, no banks, but they did have a whip with a yoke fitting on it so if you have a yoke tank, you are good to go. 2 of my tanks are DIN so luckily I brought my own DIN whip with me and they switched out the yoke for the DIN, no problem. Nice 3000psi fills. Good guys there. Fire department also has air but because there are businesses selling air, they didn't want to intrude on the community's business opportunities.
I needed 02 for my RB and I got it from Medic North. All they had were the medical connectors so once again we switched out their whip for my DIN. Good guys there as well. Max 2000psi.
As far as renting tanks...I have no idea. I brought my own as I was going to a mine site 600km north of YK. Who, as it turns out, had a kickass ~9cfm Bauer compressor with only 21 hours on the meter and a 2X4500 cylinder bank. Hasn't run in 3 years.