Right here's a pic of the stitch line and where to tape or pin only double sided tape in this area to stop it moving
and then when all pieces stitched and turned the correct way it will look like this
Then put the inner and outer together trim both pieces to the shape you require and then you can either stitch from top to bottom through both pieces to hold them together or turn the hem and stitch or finish with grosgrain all the way round like this picture.
once the grosgrain is on you can then ad your 50mm seat belt webbing to form the bridge loops and if you start to stitch the webbing from the top part of the saddle in the middle, go all the way to the side and form the loop. now the kestral loops have an adjustable pull strap and the loop is bigger than needed but it can be cinched down, I decided to just have a fixed loop that I preferred and not faff about simple is always better in my opinion.
each loop is 16" and firstly the 2" webbing is folded over to the middle from each side and stitched down then wrapped with cordura and finished with 1" webbing on the inner side both of these are 7" in length and the cordura had been folded at each end the wrapped around the red webbing so it looked nice.
you can see the stitch is simple run back and forth at one end then run round half the foots width from the edge and finish with the same back and forth at the other end.
Now i chose to pin the webbing round the saddle and then mark the loops and do off job, I think it is easier to do it on the saddle as you go. once you start stitching and you come back around to the bottom you need to stop and loop over the 2" webbing with a 1" webbing for the leg straps which is 56" overall but could be shorter, I just chose to add extra to cut later on.