I have been thinking about a create-a-gain-pattern tool under Extras. I may also allow players to set the exact proportions for each of the eight body parts in character creation (for both the player and custom girls), as an advanced mode.
I'd love that because if I understand correctly, it could be used to be build an absolute monstrosity of a woman. Like, a 600 pound, wide, tall, and padded with fat woman, but technically "thin" in a relative sense.
You could even let the player (during character creation) set the averages of each stat for the world to guide how the randomly generated girls come out on average, which would let me create a whole world of very fat mini-giantesses who weigh an average of 600 pounds each and look every pound of it, but are perfectly healthy at that weight and thus classed by the game as "thin".