Thanks a lot for your response! It really means a lot, that you and other modders put so much effort into making the game more enjoyable to others, with next to no personal gain. Huge props to you!
Now to business: The craft I made consisted of three cylindrical shapes, as well as a cone, which connected to the control module. I removed the cone and the same issue appeared. After testing it out for a bit, it seems like my Mac is simply overburdened. The shape doesn't seem to matter primarily, as small amounts of any shape load properly, but as soon as I increase the amount of shapes or their size, the game freezes. I bet the OS has something to do with this, as I'm pretty confident that a PC with the same specs could run the mod just fine. I love Mac for everyday stuff, but man.. For what they cost, they're ass for gaming!
I'm not sure if I should write this, since it feels like telling a doctor, what sickness I know I have, just by googling it. However, googling the "Receiving unhandled NULL exception" line, lead me to forums, which were explicitly talking about Unity Mac builds (not related to KSP though). I don't know if this could be a problem specific to Mac, but thought I might as well mention it. Sorry if this is an amateurish assumption.
Here are two screenshots of similar vassals with different amounts of procedural parts used. Don't ask me why the quality is so shoddy. The simpler one still loads, while the more "complex" one (and I use this word very lightly) freezes the game. Just so you can get an idea of the magnitude of the problem.
I suppose theres not much you or I can do here, since as you stated, you don't have the time or knowledge to optimize the mod sufficiently, but I still greatly appreciate your help! Stay awesome, dude!