I was pretty happy with the way the splicing turned out. Having made all of one set of whoopies and some simple unlocked splices for DIY bridge #1, the double end locked brummels were a bit of a challenge. I later found a diagram for making a locked brummel with only the free end, but it involved turning the amsteel inside out (twice) and made my brain feel like it was being turned inside out.
The bonus of using white fabric was that light pencil lines show up well and make sewing in straight lines much easier. I only used a single line of stitches for the pad pocket and did not perceive of much stress on this line of stitches. Seems that the bottom layer carries all the weight when the pad is in place. The top layer over the pad pocket stays pretty loose.
Well there are still a few loose threads, but it is improved compared to DIY #1.