Here"s an update: I decided on a lightweight poly/cotton batting, it was actually less weight than the flannel. I got it loaded on my quilt frame and I'm happy to report it is holding up and hasn't toppled over on me! Hahaha
I'm hoping to get it quilted by this evening using just large meandering to keep it looser and softer, just enough stitching to hold it together. So off to quilting I go! Thanks again for all the great advice