Do you think there might be a way to incorporate "planet density" into the formula somehow? For example, Vulcanus strikes me as a planet that is more dense than others due to it having large amounts of tungsten and other heavy metals - I would think this contributes toward its gravity more significantly than other planets, and so its size wouldn't be as large as you have it currently.

You could generate your own density values per planet and/or let other mods set their own, and then allow your mod to adjust the planet sizes accordingly.

It is certainly possible, but Vulcanus is already the largest of the planets and if we're going to set the scale of each planet individually you could do without this mod and just call Visible Planet's vp_override_planet_scale function.

Not to shoot the idea down completely, so let me know what you think.