Covering a 5th Wheel for the Winter

I live in Western NY, park my rig on pad in yard which is under trees. We get over 100" snow annually. A cover is necessary in my case. About 5 years ago I bought a 20' x 40' heavy duty silver tarp from Tractor Supply Store for around $150. I have mine installed much the same as poncho62, but my tarp also covers about halfway down on each side and the entire roof. It takes some work to install it using lots of rope, but it is extremely tight and secure and is not affected by the wind. No holes after 5 years use. It does not leave marks on the exterior walls. I also have maxair vent covers on all 4 roof vents. I leave each roof vent cracked for ventilation. Never any mold or moisture problems.
I bought a $400 Tyvek type rv cover once and it lasted one season.