In the depths of a Wisconsin winter, a few days before the end of 2020, Emily Ford went backpacking. Nearly 1,200 miles of snowy trail stretched before her when she set off from Potawatomi State Park in Sturgeon Bay, on the edge of Lake Michigan. Accompanied only by Diggins—a friend’s sled dog, borrowed for the expedition—Ford planned to tackle the Ice Age National Scenic Trail. If she finished, she would be only the second documented person to complete the trail in winter, and the first woman and first person of…