Update from Teri D. I wound up deciding that I didn't want to overthink this by trying a double batting and obsessing about how the back would look. Well, actually, I decided that I wanted the quilt DONE.......(!!!)
So, I did a pieced backing (per the Craftsy class) with "improvisational blocks" and then just sandwiched the quilt and treated it like a "regular" quilt. The challenging part was laying out the sandwich to assure that the back was squared up straight in relation to the top so it didn't shift and wind up "wonky". I quilted as usual from the front and, since it was a sampler, there were a variety of quilting motifs. I was afraid that it would look very weird on the back to have no relationship between the quilting and the design -- but it doesn't. In fact, I've had several folks tell me that the back is more interesting because the quilting DOESN'T follow the blocks -- the front is a very traditional sampler and the back is more like a Mondrian piece.