Good for you!
Am looking forward to your pictures.
By the way - - did you consider that quilt shops usually sell backing fabric which ranges from 96" to 120" wide?
Buy two yards of that (or whatever it takes to get to the width you need) and you have a back with no seams. Plus, you will usually have some fabric leftover for your "stash" ...
It is just another option to look into for your next quilt.