Thanks for the suggestion! If this becomes a commonly requested feature, we'll definitely look into what it would take to support that :)
Viewing post in Will this Game be expanded to be a full time Mistress?
We'll probably implement changing clothing and buying things for your favorite Mistress before we do any 3D model customization. That's an entirely different system that would take a good chunk of dedicated time to pull off. It wouldn't just be a matter of building the underlying system, but also modifying the art so that the clothes would fit different body types. Definitely far from being a possiblity. Sorry! :)