When I was working on a king size, I was petrified that I would have puckers. Was using a DSM. First, I sprayed all my layers together and then I hand basted. Say one long straight stitch and then a short one to the left. Sort of like a zig zag and repeated with the long. The puppy didn't shift at all.
If I ever do another one that size, I'm sure going to do it that way again.