Kevin I will explain the conditions we zone 6 PA people live through.
Generally
Sept. Rain, Rain, Rain, at least 3 weeks every day that month
Oct, Rain, by morning Freezing Rain, Snow, Freezing Rain on top of the Snow
Nov. Spring rains, Spring Rains, Spring Rain, Freezing rain, Snow maybe
Dec. Rain today, Ice tomorrow, Spring Rain, Ice storm, Snow.
Jan - March.....Rain, Snow for weeks, Freezing Rain, Then Snow until March
So my zone 6 is not a good indicator to a zone 4 that gets cold stay cold with maybe some snow or a lot of snow. My type of winter is different with the moisture, freeze, before there is a layer of snow for insulation. You have constant moisture and drastic temp change in a matter of hours changing that frozen block of ice from water to ice then back to ice constantly.
We have so many warm up enough to dump a small lake of water to freeze then a layer cake of ice, snow, ice.
I grow all my succulents on a 1-2 feet layer of gravel, topped with a foot of pine needles, and a thin layer of soil on top.