YIKES! I've only done up to a twin size but what works for me, is to lay out the quilt on my cutting table, then slip an ironing pad underneath. You have keep moving the pad from spot to spot, but it gets the job done. I do this, when I glue baste, to set the glue. If you don't have an ironing pad/ironing mat, do a Google search on them. They're fairly easy to find and come in different sizes.