I'd love to be able to more easily self-insert myself as the protagonist with a basic character customizer. Though as an artiat, I understand how much effort the smalleat change(s) can be.
So some examples of what I'd consider "easier" additions might include: hair style/color, eye color, facial hair, etc.
A harder addition would be clothing and/or body types, for example: feminine/androgynous, skinny, muscle skinny, average, dadbod/chubby, built, and muscular/giga-chad.
Depending on how the game was made, cock size for not just the player character, but even the whole cast might be a relatively simple change OR a massive undertaking.
That said? I 100% love, appreciate & respect this game, your time and effort and thank you dor your generosity in sharing it!