I didn't use that much background fabric. I bought 10 or 11 yrds. to do the sashing, kite background, plain tris, scallops (which were larger than the pattern called for) and binding. I used about 4 different creme backgrounds for the blocks and didn't buy them all at one time. My quilt is kind of scrappy...but not. The software is generous with the measurements.
Maybe someone who used the same background for everything will tell you how much they bought.
You do have some great LQSs over your direction!