Get a big 'ole needle. I use a giant embroidery needle. Thread it with sturdy thread. The color doesn't matter. I used fluorescent orange so that y'all could see it.
Put a stitch into the seam allowance near the stitched corner.
Tie it off snugly. You don't want this to come untied while you are trying to turn your loop!!
Gently insert the needle between the two layers of fabric and in between two stitches as close to the point where you pivoted your stitching as possible.
"Thread" your big needle through the loop. Be careful not to come through the fabric. This is why I use a big needle. It is easier to keep a hold of!
Here is what is likely looks like up top. You can see my orange knot at the corner. The fabric is bunching up around the knot, trying to turn!
With your fingers, gently tuck the knot into the loop.
Then VERY gently so as to not break your thread or your knot, pull the needle while working the fabric over itself.
When you see the corner coming out the end, you can just yank it the rest of the way. You're home free!
Now you just have to straighten it out and press it. An added bonus is that since you pulled the loop through at the corner, your stitched corner comes out nice and sharp, with a very professional look.
Tomorrow I'll tackle lining up straps within the facing.