Dom bag awnings are pretty common to folding tent trailers. Here's a link to a supplier, you'll find the bag awning stuff about halfway down the page:
Thanks for posting that link. I am sure I have seen that before but never saved it. Now I have. Those prices seem quite resonable. What would a 13' use, an 8' awning
Just over $300 for an awning and screen room seems OK to me.