Its a small world out there! My son is in the Air Force and also lives in North Pole!
As for fuel economy, I traded a 2001 Dodge Ram with 5.9 for my 2013. On a good week I would see 10 mpg with almost 100 hp less. Am getting between 14.5 and 15.5 running around my local area in downstate IL since the weather headed away from summer temps. With 2600 miles to date, I've seen as high as 22 on average keeping speeds at 60 or less for short highway trips. Current setting indicates 14.7 since last fill and there has been no travel outside the area. Needless to say, I'm liking it a lot.
That being said, I do know with -30 to -40 temps you see where you're at will run that number down quite a bit. Not only the long idle warm up but the thickness of the bearing greases, engine oil, trans fluid, axle lube and all will add aditional load on the engine especially on short trips. If you're traveling some distances like my son does from NP to the base, mileage will be a little better. The engine heater helps a lot for the engine, but it doesn't do anything for the rest of the drivetrain.
Now, once the brutal winter is done, you will see similar economy to what we're seeing in the lower 48. As for the power, there simply is no comparison. Once things are warmed up and those turbos do thier thing, hold on, its a great ride!
Hope this helps you in your decision.