AH! I love your Actor!AU for part 4! I was thinking about something similar a while back but for the entire anime cast. Ex: Young Dio being the biggest dog lover, playing with Danny during breaks every chance he could get before they finished filming episode 1. Oldseph is just as much of a prankster/trickster on set as his in-show character. The cast loves to joke around, but he is THE undefeated champion of silly on-set shenanigans. And Jotaro is warm and easy-going, and gives great hugs.
I honestly just am in love with everyone being so warm and nice off the camera, I want them all to get along and be great off-set and then turn into UTTER ASSHOLES in front of the camera, THIS IS GOOD STUFF