Don't know if you've got it all figured out yet but, we had the same dilemma.
I purchased a durable cotton/polyester fabric
and the good quality mildew resistant quilt backing. Captain
Eric screwed and/or glued (only where necessary) a few "nailers" and we used stainless staples to adhere the fabric
on the corners and center. Covered the margins with mahogany molding, and voila!
Now at 2 years and looks great! While we know it's not permanent (what is?), it cost a lot less in time and money
and looks great!
Wynki & Eric