I'm wondering how hard it would be....

Sorry I haven't, but I wouldn't think it would be too hard as long as the frame is in good condition. Do you already have a frame?

Well, I found this place that sells refurbished frames for around $30.00, and they even sell the pattern for the cloth cover. However, my sewing skills aren't perfect, lol!

http://www.shootingstarhistory.com/merchantile.html#Parasol

Here's a sort of how to here not sure if it's helpful or not.