Out of curiosity I looked up Whitehorse weather. I was going to suggest you get out today and shoot something since it looked like your last "warm" day for awhile (maybe months). I think the predicted high was 10 degrees, I assume Celsius. But then I went to your Flickr pages and saw you and your friends riding your bikes in 40 below weather! I think you can handle cold weather 4X5 shooting just fine. It will be interesting to see how the camera likes it. Once when I was much younger I did a shot at -10F. I set up and focused, then removed the lens and board and slipped them in an inside pocket to keep the shutter warm until I was ready to shoot (I was waiting for a train to come through). It looks like you have a lot of interesting subject matter in your area to use 4X5 on, especially the old mining equipment. Have fun!