Pigfish trade option is available if you take her panties, when she wears white leggins. So the seller can go to the barracks and get the 'proof'.
As far as I remember 'no leggings' option is available at lvl4.
Yep, lvl 4 is max for now, working on getting her to lvl5, but it may take some time, don't want to do it too fast. Besides I want to make more animations
Thx!