How are you quilting it? If doing it on a rack setup you can easily put another layer of fabric or batting. The Heron Pond quilt I recently posted (
http://www.quiltingboard.com/picture...c-t265846.html had a dark navy blue batik backing and the sky had pieces that were very light. At first the client only wanted a single layer of batting but I could see the navy would shadow through so we did two layers and that solved the problem. but if you are hand quilting or FMQ on a domestic double batting will be very hard to deal with. However a layer of white fabric would hardly be noticeable, other than the extra weight.