I feel really dumb asking this after making so many quilts, but, I hav always used full cloth backing. I would like to make a pieced backing, but this seems hard. Is it like making 2 quilts?

Not at all!! Just use large pieces of yardage to put the back together. I have only once bought the larger baking size fabric. Make sure that it is about 3" larger around all edges!!!

It's not hard--just a pain to do all the math. Just keep sewing pieces together until it is at least 3 inches larger all around than your top. You can also do a second top if you'd like but I only do the "2 for 1" tops on baby quilts. Again, it's a pain to do the math to make the second side and make it larger than the first--final wide border usually works.

:D

Has anyone tried this method for pieced backing?

I piece just about all my backs. Either so it is all the same fabric, or so it looks like a frame on the back. Here is an example from my avatar quilt. Not hard at all.

Oops! Here's the second page of the diagonal-pieced method -- I can't figure out how to make the diagonal cut on such a long piece of fabric -- this method would save a lot of fabric if I could figure it out!

OMG!
too much math this early in the morning!
I have never seen that method
I will look at it again after a few more cups of coffee!

If you are sending this to a long arm quilter, check with her which way she likes her seam to go. I like my customers to run their seams parallel to my poles. It makes rolling it much smoother. If you are doing this on your domestic or hand quilting than it should not make a difference.

Hmmm, interesting! Besides using less fabric, I thought it would be nice to have the seam running diagonally because there isn't a "lump" when putting it on the frame.