Mosquito head net. Also called a barrier net by the U.S.A.F. and a metal cup might be better than the thermos flask's lid.
Perhaps you should ask your employer for formal survival training?

Well, 'tis the season - I've got the winter parka out already. I stuff my toque in the hood for easy use.
I do have the gloves, both finger gloves and insulated work gloves which I just updated yesterday.
Socks - Yeah, it came to me yesterday that I should look at putting some extra clothes in kit; just which ones and what type I haven't decided on.
Cord/rope! Oh what a dope I am - I went through my entire list and realized I had no cordage! And I've got a couple hundred feet waiting to be allocated in my camping gear...
Bug dope - well, only when in season! In the summer I carry my golf clubs in the trunk - I'm always "prepared" to hit the links! <img src="/images/graemlins/laugh.gif" alt="" /> I carry bug dope and sun screen in the bag.
Got the boots covered - my work safety boots are in there in case I need to go to a construction site.

Speaking of vehicle kits - it came in handy today. I came home from a road trip to find my car had a flat tire apparently due to belt failure. I guess I'm gonna change to my winter tires a week sooner that I thought I was! :-(
After unloading the trunk contents into the back seats (that took longer than expected) it took about 15-20 min. to finish the change. I did use a couple of things from my kit - the WD-40 and the shop towels. My foot air pump was totally useless as it broke at the hose elbow! The store is going to get an earfull tomorrow!

BTW, future advice to all ETS readers. Even if you have the greatest and most complete vehicles kits around, make sure your spare tire is fully inflated. Nothing worse than realizing you can't change into a flat tire. Thankfully - mine was full due to a spot check a few days ago!

One thing that you might also want to consider are the things that caterers use to keep pans of food warm. They have a specific name that I can never remember. Some are quite good, rated for 8 hours or more, and if they are accidentally knocked over, they don't spill. Very safe. Of course, they all come with disclaimers for proper use, use at your own risk. I am looking for some for my own vehicles.

Several pairs of spare socks. Good thinking.
In cold weather, wet socks are very bad news. Even simple perspiration will wet them. A lot of people mistakenly think that because it is cold, they don't sweat. That's a quick way to crippled feet.
One thing you should check is the amount of insulation your sleeping bag has around your feet and lower legs. Otherwise you could wind up with frostbite.
A balaclava to protect your head and face might be wise. Having your face inside the bag will lead to a damp sleeping bag. That will drastically reduce it's rating.
I think that you need to develop a through understanding of arctic survival. -40 is not exactly the most forgiving of environments.