Instead of FMQ, have you considered using your walking foot (and feed dogs up) to make wavy lines? As long as the curves are big, the walking foot works great for this. You could, for example, mark the curved borders shown in the link and sew them with a walking foot.
Another option is to just make wavy lines across the quilt, or wavy lines in both directions so you have a wavy cross-hatch.
I didn't use the specific product in the link, but I did try to quilt over paper once. I found removal of the paper tedious, plus it was hard to get some of it out from under the stitches.