I've been making back/front interchanagable for ages. Even my Dear Jane is double sided and I quilted it by hand
I started doing it because I didn't want to buy yardage when I already had a closet full of fabric.
Now I do it because I like it, because each double top put together halves the cost of quilting and halves the storage space.
When I was hand quilting still, I'd make them both identical sized, but for my machine quilter I give the under side about a 7" float all around. Wonderful!
this is my most recent double sided quilt. Not fancy on the back but good use of stash