I made a wallhanging that was asymmetric at the top. With the batting, I added a stiffener in the top half (maybe it was Timtex) to keep it from flopping. If you've already sandwiched and quilted it, maybe you could just baste something like that on the back. I then put the hanging sleeve partway down from the top. Hope this helps!

You probably need to contact the people who are putting on the show. Sometimes they don't allow any quilts with special hanging requirements. If they do allow them for the show you are interested in, maybe they can give you some advice about what you need to provide.

I've trying to finish a wallhanging for a quilt show this coming weekend. What would be the best way to stabilize the arched top and what would be the easiest way to hang it? At this time I have no info on what is allowed for hanging at the show.