I finally received my 108 in. Quilter's Choice backing fabric. It was not stiff, but is pretty loosely woven. I will go ahead and use it for the back of my project, but will not try to quilt this project in sections and bring the backing to the front and stitch down between sections as in fun & done quilting as I had intended to do.
Next time I order backing I will try one that is not the least expensive. I'm sure that it will be better.