The series of step by step operations at the top of this page is on hold for the moment. For that, i need to take many steps backward, and in that process, I made another breakthrough in another area, an area on which this operation depends. So, I'll be working on that for awhile, and once sorted out, I'll start this idea up again, only from a number of steps back. Sorry for the wiplash effect, folks, but that is just a taste of what this entire project has been like for me. Still, it is a technique that is working. Little things here and there add up to much greater perfection in the long run. Even this interruption is valuable, as the more early problems get eliminated, the less of them I carry into the next operations. Obvious good logistics.
However, on those images at the top of this page, I failed to clarify the boolean operation I'd used to make my cuts. From the 3D Edit tab, I choose Solid Drill/stencil. Also, after many problems that kept popping up with every step of this operation, I finally got in the habit of running Senecas script, Mesh cleanup.pl, between every step. That seemed to eliminate all those problems.
Back to the drawing board, friends.