I have not had a problem with back wrinkles but you need a large space and though not easy on the knees or back, this is how I do. I place my backing wrong side up, on the floor and duct tape every couple feet all around, pulling taut as you go. Lay my batting on top, walking out any wrinkles. Then place my top And starting in the center pin the heck out of it. I can’t pin much at a time, taking breaks, but it does the job for me. I rather do that than end up having a problem later. Not easy at my age (today is my birthday again-lol) but doable. I quilt on a sit down long arm and mostly quilt queens but have made a few King size. I ALWAYS start quilting dead center and work my way out.