Robe a L'Anglaise: Bodice Mock-up, Or The Dart Of Possible Doom?

I was finally able to get to fitting the muslin mock-up of the JP Ryan pattern for my robe a l'Anglaise today.
Also utilizing my new Uniquely You dress form; I still need to do more fitting on her to get her closer to my uncorseted shape, but with my pair of (crappy) 18th century stays, she did just fine as a fitting reference.

At the fabric store today, I also picked up some cotton linen, for both a chemise and lining for the bodice. Though, I may want to pick up something a tad heavier to line the bodice.
While my muslin currently has the closed front, I will be making this dress as a polonaise with a zone front, in the very late 1770s style.

My own odd fitting technique, as I am not sure I have ever seen anyone do this, was to instead take in the excess fabric in what would be considered the "middle" of the front bodice piece making a dart or tuck. The front and sides of the bodice are cut as one in this particular pattern, and I have been wracking my brain as to where I have ever seen a gown from this era with true side seams.
I'm sure I have, but either way, this is an option that worked for me.
As someone with an "X" body type, when corseted or in stays, my waistline-to-bust ratio increases even more. This always means I need to take in the waist on just about every pattern I sew from quite drastically if I'm going by bust measurement. This was no different, and after fiddling with the back seams, it seemed to just make the wrinkling worse...it's about here where I begin to call them "wrong-kles".
It's as if the pattern makes up a shapeless tube completely ignoring the soft, and in some cases extreme, conical shape of the classic 18th century bodice.
I also extended the back point to a slightly longer length, creating a more flattering and slenderizing line.

So out of curiosity, and I probably did this in the most wrong way possible according to fellow seamstresses; I made a dart where a side seam would be. This took in all the excess "wrong-kles" and created a smooth fit.
So far so good. At least the fashion fabric I'm using is a cute cotton print I picked up on sale and not totally historically accurate. If I screw this up, I won't be out much cash.....but nonetheless frustrated.

The 'tuck'...am I a total rebel or have others done this too?

Note that this tuck will not be in the final bodice, but I will be using this as the new front pattern piece for it. You can also see how the tuck created a sharper arch at the waistline edge, yet in many extant gowns and bodices, I have seen this. I may smooth it out a bit more as I go, lessening the Gothic arch onto a more Romanesque one, but once those edges are clipped and turned, it'll straighten out on it's own.