I've used fleece. I still use batting to make it stable. Then sew it "envelope" style and turn it right side out. Rather than quilting it and risk it puckering, I just put "tacks" in it every so many inches.
Just made a baby quilt this week end and used minkee fabric for the back. Very soft and slippery and I was worried about it stretching. So I did it this way.
Will load pics later and post it for you.