So as I bimble along on this LACMA-Sacque-ma, diligently cutting out all the many pieces, and saving every little scrap, I'm getting the feeling that I'm not going to have enough fabric left to recreate the trims on the original dress.
Oh Snap....
Oh, I fully intend to stitch together every minuscule piece of cabbage in a last ditch effort to get those hundreds of inches needed to do the pleats, but it's not looking good.  So, just to be prepared for epic failure, here are some trim options that are *not* made with matching fabric.  This wasn't very common, it seems, but at least I won't have a naked sacque, if it comes to that...

The Met, 1770-75. This Robe has frothy bits on the front.
The Met, 1770-75. Here's a closeup of the frothy bits. I think this works because the froth and the gown fabric are the same color - it might not work so well with the blue fabric.
The Met, 1740s - this gown has a crochet (?) net trim with fly fringe on the edges
Here's a closeup
VandA, 1775-80 - this appears to be puffed blue silk over embroidery.
KCI, c. 1760 - trimmed with lace (but also quite a lot of self fabric)
Arizona Costume Institute, c. 1760 - trimmed with gold lace.
Royal Ontario Museum, 1750s - trimmed with silver. A viable option.
MFA, 1775 - another trimmed in metallic lace.
The Met, 1750-75 - this one is trimmed in passementarie. 10 tons of it.
Here's a closeup of the above. I...I don't think I'll be attempting this madness.
The Met, 1770 (click through for the whole dress) - I think this looks stupid, but it *is* an option.
Most of the gowns showing non-matching trims appear to be a little later than my inspiration dress.  Of course, what I really want is to somehow schnarg out enough yardage to make all the trims, but I might be gettin' jiggy with the silver spray paint on some lace instead, which I could live with.  It wouldn't be a re-creation at that point, but at least it would still look pretty cool. :-)