Making a picture frame. I need to give the plastic cover sheet a slight convex curve outwards (in one dimension, fortunately). 1/8" over 30 inches. I want to do a decent job of it appearance-wise. No visible gaps between frame and plastic.

Using the attached formula, I get a radius of 900 inches. 75 feet. So I'm not going to be building a simple jig with an arm to hold my router.

Any ideas?