To answer Maride's question, You can not find a piece of batting big enough, you can however sew, and fuse two pieces together to make one very big one.
As for the quilt as you go, this would have worked had I just started planning it, but I am 90% done with the top piece....
While I was sitting here asking this question, it came to me that I could do a brick wall type pattern on it, instead of quilting it, sew it. Since it is all various sized strips sewn together I think that may be kind of fitting..I will have to post some pictures later today, once the kids are off at school.