We do have rags, it's sr.png in game\content\items\body. Also we have some cuffs and collars. Collars are in items\amulet, handcuffs in feet folder and handcuffs in wrist folder.
Of course they also could be nakes + collar and cuffs, if rags will be too ugly or too complex. Btw our rags icon is pretty ugly already, but we were unable to find anything better for 2 (!) years. If you could render a better icon, that would helped.
That's for untrained ones. Trained ones, ie 100% loyal, wear usual clothes, just as free girls. And random free girls could use any clothes you like.
You are welcomed to try and render everything, but I imagine it might take a lot of time.
There is indeed a gap between how girls look and what they have equipped. I think it's unrealistic to render everything, currently we have about 250 clothing items (excluding weapons and consumables).