I actually am planning to do a Lottie cosplay as well. My main issue is how to get the volume in the back of the dress.
The silhouette is closest to the 1750s French court dresses, but when she is tripped at the party you see she is wearing a hoopskirt closer to those in 1860.
To add on to the inaccuracy of wearing a pannier, she has a bunch of volume in the back of her dress as well.
I don't think a full petticoat will do me much good with how voluminous her dress is. I was thinking of constructing a large bustle piece that I would wear separate from the pannier. However I am not sure how I would make such a piece or where to even begin. Any advice?