I'm from MI, too - we put strips of plastic over the pop door, about 3" wide, and overlapping 3/4". They push right through it without issue. I got the plastic at Home Depot - bought a foot of clear carpet runner stuff in the carpet aisle (not the stuff with the little spikes on the back, though - this is smooth, both sides). It works great, and I'm hoping to be able to leave the door open during the day, and shut at night.