Hi,
I'm in Zone 6 NY, so my conditions are at least very similar to yours. I don't leave any VFT or Sarrs outside all year, it just get's too cold for too long. I lost immature VFTs, not this past winter, but the one before it where it snowed like every other week even though my indoor dormancy spot has served me well all the years before and since. I wouldn't risk it if I were you, I let them come out of dormancy outdoors naturally, stay the summer, then naturally go into dormancy outdoors in the fall, but I keep them protected indoors when they are dormant.

The only ones that MAY survive are the purple pitcher plant.

Thanks for your input,i think the safe way is in a cold garage for winter.