Mitered binding

I've done 90 degree corners for years on my binding. I willingly agreed to bind my daughter's quilt that had hexagon shapes on the edge of the quilt knowing it would be challenging. Not so much difficult as it just tedious. Angela counted the miters 2 nights ago; 256 outer points on her king size quilt, she did not count inside corners but I'm assuming the number is about the same. It takes 20 minutes to do the machine work on 7 miters.... That's about 12.5 hours of machine stitching.I'm spacing it out over 3 days. We moved the sewing machine to the dining room table so I wouldn't be hidden away in the sewing room. And I have the whole table to hold the weight of the quilt...very important, since it is so heavy.
I watched a few tutes about mitering and this one is good about the inside corner. Then this one about the outside corner.

 Here you can see the binding started....I'm about 14 done. The only thing I added to the above tutorials is to

 stay stitch the quilt, all the way around with a small stitch a scant 1/4" in from the edge. Then when I clip the seam I clip almost to the stay-stitching. I did not want to be guessing where to stop and start the stitching. Looking on the backside, since the front side is hidden by the binding, I insert a pin at the 1/4" mark made by the stay-stitching through to the sewing side of the binding, then repin it on the front side and then stitch it to the pin. (You can see the water soluble marking on the front that I used when quilting to know not to quilt where the binding would be. That mark did no good at the binding stage since I could not see it from either side.