you can try weight gain
realistically, where on the body would the added weight go?
her face? no, i don't want to
breasts? that's the one part where weight gain is already implemented
belly? she'll be stuffed 99% of the time so you wouldn't even notice
ass/thighs? she's facing towards you, so you'd barely see the ass
it seems like a lot of effort for something that is far less noticeable than you would initially think. at most, i could make a chubby version of 0L-3L (only affecting the belly) and have stage 4 use 5L instead, and so on