Oh man, regency is deceptive. It LOOKS so simple, but there is a lot going on with those dresses. For what it's worth, I have NEVER been able to get a drop-front to work for me, so you're miles ahead of me there!

Also, if it helps, I cheat all the time on undies. MANY people substitute tank tops, a comfy nightie, or whatever works in place of a chemise...I often wear leggings instead of drawers if it's cold, or pajama shorts if it's hot. Even for super high-accuracy museum events...if nobody sees it, do what works!