I did something not long ago that might be a suggestion. I did stitch in the ditch, but not all the way across the quilt, because there weren't seams all the way across just like this quilt. Just in little bits here and there where it needed to be according to how close the stitching needed to be for the batting. Then I brought the threads to the backside and tied them off. I didn't want any stitching showing on the top and it turned out fine. It is a bit time consuming, stitch in the ditch does also take a bit of practice and skill, but I think over all it is easier to do the FMQ.