I tried almost everything mentioned here... and still had puckers. I finally bought one of the John Flynn Frames (seems to be one of those love-em-or-hate-em things). The first quilt I tried came out perfectly without puckers. The "good" quilt that began this whole thing is patiently awaiting my quilting skill to improve sufficiently to do it on the Flynn Frame.
It does take a large space to use which could be a problem and the quilting space is limited to the width of your sewing machine throat. But -- no puckers.