What about using a fleece backing for it and no batting? A good grade of flannel would work, but I have never seen flannel in a black or dark blue. Another idea would be to do it in blue jean material and no batting. That might be too heavy although they have different jean fabric weights. I'm trying to think of something that would have some substance but not be over whelming, and would be washable. There are a lot of options in the clothing fabric sections at JoAnn's. It just has to be washable. Double knit made some fairly warm, lightweight quilts.