Thank you for your comments. My experience during 10 years of full timing, using the Girard Topper Product was wonderful. They mount to the coach the complete opposite as other toppers do. The casing is mounted on the coach side wall, which creates the pitch you mention. They also have a small sweeping broom that contacts the cloth, located at the front of the casing. The water pooling is a definite contributor to the life span of the cloth and threads of the stitching. I had a friend, RIP, that replaced the toppers on a 2005 Dynasty 3 slide in 2006 to Girard Toppers. Cost him 4K+. He was full timing and kept the coach till 2014. So amortizing that over that duration, it's a no brainer.
You may want to consider designing some brackets or ??? to simply reverse the current installation of Carefree, for example, and you would obtain the desired preferred pitch. I always thought that you could / would make stainless steel coils springs that would sell very well. A spring coiling machine is not that expensive and there is a market waiting for the product that you currently service. I have attached a link to a Girard Product Video for the convenience of our members to review.
Paul A https://youtu.be/9lyt70Vl71c