I have done a couple of stained glass pieces. You are basically correct in the way you plan to do it. I would use a white background. I know you plan to make a quilt of some type; however I would like to share something that is cool with you.
Fifteen or so years ago when they opened Tammarak (sp), the West Virginia arts center I was traveling a lot from NC to Indiana. I awaited the opening with the greatest of anticipation. Finally, it opened. I stopped allowing myself lots of time to admire all. Well, when I walked in right in front of me was a beautiful stained glass window. I thought what a wonderful depiction of one of WV's real arts, glasswork. As I got closer to it to look, I realized it was not glass at all. It was fabric. They had done the fabric stained glass, backed it in white and hung it where the sun could shine through it. I have never forgotten that one stained glass. I did a small butterfly that way and I have it in my window to brighten my mornings.