I drove many winters in Mustangs in Michigan.
I never put anything in my trunk, just used the proper tires.
I am confused at to why the OP thinks that his Blizzaks didn't work. If he got through 17" of snow, that is way, waaaaay beyond anything Blizzaks (or any tires) are supposed to do.
Sounds to me like th Blizzaks did very well, and the OP has little experience driving a Mustang in the wwinter.