I do similar for my gravel driveway, cut 2.5" sch 40 lengthwise, align holes for cutting blade and use post bolts to attach. It'll be 20 degress but ground isn't frozen so rocks are loose. When I added sch 40 piece of pvc, it sort of rolls over the stones.. by no means perfect. However avoids 90% of the rock and works great over sand or grass. I noticed that it is better in the virgin snow vs tracks. I plan to bring fence pipe to machine shop in spring for length cuts. Snowblower is heavy and sch 40 does well but plastic +cold = cracks.