Phil, the sizing was a concern and I believe magna shade is cut to your coach's size. The point you make about convective heating, however, is a very good one that I hadn't thought of. Since it's not a vacuum, anything caught between the windshield and the cover will become a furnace that will end up heating the coach. So I guess Cajun is right in saying you should stop the heat on the outside. Magneshade...sold. BTW, I did talk to Roger at Goshen and I have no doubt it is a great product. Just wanted to explore all options.