John,
Welcome to the forum! Many fig trees are sent bare root from nurseries, as well as other trees. If I lived where it snowed, I'd be tempted to wrap them in damp sphangum moss in plastic with a blanket to keep them in the dark, and in a cold place until I was ready to bring them out and introduce them to spring.
This is a California native talking, who knows nothing about the necessity of storing figs in the winter, but I do know that figs and grapevines are so much alike, it's hard to separate them in my mind. They both are determined to survive, they both ship bare root, they both go dormant, and in spring, they bless you with lush green growth and fruit which ripens in summr and fall.
We'll be moving over 100 vines and trees, some in containers, some in-ground to another property soon, and I know there will be set backs. It is what it is.
Good luck with your 40 trees!
Suzi