When there is piping involved I put my binding on upside down and backwards! - this is the method taught by Susan Cleveland and it works great.
So you join the binding strips with diagonal seams as shown before until you have the length needed to go all around the quilt plus some extra for insurance and joining.
Press seams open raw edges together, right sides out. Leave a tail unsewn of about 10". (There are easier ways to do this, which I use on my small quilts, but this is hopefully a show quilt and I'll try to make it top notch.)
I pin baste over the piping (on the ironing board again to avoid the stretching monster) then sew from the back using the piping seam as a guide.
When I get to the corner I stop where the piping seam intersects and drive off the corner diagonally...remove from the machine and fix the corner like you normally would.