The Mock-Up Commences (or does it?)

Here is the start of the mock-up with a pair of my DH’s old pants:

They are cotton twill, a great, inexpensive (free!) stand-in for coutil.  However, what a waste of 100% cotton! I can do a sloppy, fast job and toss them OR I can treat this toile as important from the start, and in the end, have a well-worn, soft twill steampunk edition of this corset. I don’t foresee needing to cut them apart, which is what the toile is for – fitting, marking, dismantling, then creating an entirely new, trued pattern. I guess I’ll just have to wait and see how it comes out.
Here’s today’s conundrum: See the ending place in the Waugh diagram for the elastic placement on the front? [The top piece in the picture.]  Where the heck does that end?  In this drawing, it just stops.  That makes no sense, because I’d have to fold my elastic under to finish it creating a huge lump near the center front of the garment’s waist, or it slips in-between two layers of corset material - the fashion fabric and the strength layer.  Now, that sounds like a reasonable option until I consider there won’t be anything for it to slide into.  I plan on flat-lining coutil to fashion fabric, treating the two fabrics as one piece, one layer.  There will be no seam to speak of to tuck it into.  I have two options.  One is to lay an additional bone casing in up against the busk, thus covering the elastic; the other option is to ignore the drawing and carry the elastic over to the busk and bury it in there someplace.  I like the first option much better.  It strengthens the over-all garment, and leaves no lump.