When I toured the quilt studio of a retired professional quilter (Melody Johnson of Fibermania) I noticed that she dosen't try to hide knots on the back of her wall hanging quilts. They are beautiful and she sells them that way. Maybe you are being too hard on your self. Instead of trying to hide the knots could you clip them off, unpick a short distance, re-knot and hide, then re-quilt the small space using another method to knot ends.