I don't think it'd be a lot of work, honestly. It'd be just like showing Perry without glasses (if Robert breaks them) or showing Ian with a black eye in Chapter 2. For example, to show the black eye, Eva uses the code:
"if v1_fight = True; $ ian = hurt"
Considering that Ian has a sporty build already (he's pretty buff), the only thing you'd have to do is define his muscles a bit, making him look more ripped. And to show the muscles she can use a similar command "If ian_athletics > 4; $ ian_muscles" or something like that. The artists who colorize sex scenes, however, will have a bit more on their shoulders.