Now that that is said and done, I was sketching out a picture and trying to play around with my patterns to come up with what I wanted. Didn't work. So I went back to the main instructions with a few alterations to the necklines since I would be wearing it with the ELC gown and not the basic one.
So far I've got the darts done in the front, and right now I need to hand sew my casing for the ribbon drawstring at the neckline. The instructions show it to be on the outside, but since my gown is sheer, I want any extra drawstrings to be inside and not showing through the gown!
After that, I'll add the boning to the front, add buttons to the back, and check the fit once again.
From a screen cap of the '95 version of Sense & Sensibility, you can see that Marianne is definitely wearing a bodiced petticoat underneath a sheer gown. This, and Lydia's famous petticoat from the '95 version of Pride and Prejudice are my inspirations.
It also appears that the top part is made out of sturdy stiff fabric. I didn't think of making the top part of mine out of stiffer fabric, unfortunately. I'm beginning to think that two layers of muslin isn't going to cut it. =P