This was my second winter with my Boxster as a daily driver. Bought all seasons for it last winter and they were worthless. This winter I bought Blizzaks and it gets around great. You don't mention what size tires you have. Mine are 18's and the Blizzaks cost $1100. If you have 17's you will get by much cheaper and an extra set of wheels will be easier / cheaper to come by. Not so with 18's - you could spend an additional $1k for wheels. Might need to throw a few more bucks into the tire estimate depending on what size tires you have.
We had an extended cold streak last month in Omaha where the temps didn't get out of single digits for the high. You could really tell the difference in how "limber" (or lack thereof) the car was at these temps. It made lots of creaks and groans I've never heard in 1.5 yrs of ownership. It certainly got nowhere near ND lows. I can't imagine how hard -30 would be on any car, let alone a sometimes fragile sports car.
My $.02 says put it away and buy a beater. The wear and tear will be multiplied in those conditions. You're still young enough that a year seems to take forever to pass (that will change as you age), but your tour will be done before you know it and you can take your pristine Boxster to warmer climates.
BTW
I concur with Brucelee. Thank you for defending our great nation.
Terry