I seen one a few years ago on a MH out in AZ. It was metal and opened up when the awning was out and closed over it when they retracted the awning. I can't help you on where to get one, but I know they're out there.
Have you tried calling your RV dealer?
2008 Cruiser CF26RK
2013 Ford Eco-Boost
Heavy duty payload - Max tow
A&E makes one in their top of the line model. But you have to buy it as an assembly. I don't know of any that you can buy separately and add on over a standard model. However, I haven't looked for one inquite a while so things may have changed.