If you have spray basted and pinned, you shouldn't have any problem with quilting in the way you have planned. I have used minky as backing for several quilts and have not had any problems. I pin baste only, do use batting, and do free motion quilting on my domestic sewing machine. Do usually using do some SID to stabilize before FMQ, minky or not. Hope you will be able to post pictures of your quilt some time.