Idea: Make a frilly dress that fits her at her max size and use a sequential series of replacable bindings designed to give under certain thresholds. Basically a huge dress stylishly paired down until more room is required.
Then no matter what kind of night she’s having she at least wont ruin a whole dress!
Or what if the dress was enchanted to always fit the wearer?
Hmm, since her breaststroke can go up to universal magnitude, the caster would probably have to have some really strong magic tho…
Then no matter what kind of night she’s having she at least wont ruin a whole dress!