Overwintering:
Store cool enough to keep trees dormant, warm enough to prevent freezing, moist enough to prevent root dehydration, and avoid desiccating winds. You have to make these things, happen. Bad things will be the result when you don't. Fig trees need protection in other than tropical/Mediterranean climates.
Suggestions in post #7 are probably your best best...(I'm sure you will be adding more figs to your collection), and storing in a cool, garage is more convenient when the "fig shuffle" starts next spring. Move your trees out - probably sometime in April - when days are warm, and then move them right back into the cool garage at night. Daytime out, nighttime in. Continue this shuffle routine, until temps stabilized, and can support the newly sprouted growth. Avoid at all costs, any freezing of the new growth. This can extend your growing/ripening season by about a month, and may allow you to ripen two crops of figs....depending on the variety. Match the ripening times of each variety to your climate zone.
Good luck.
Frank