We actually ended up seeing Dr. Robinson, which I was a little apprehensive about, but he was great with Rosie, got her all cleaned up, removed some dead tissue and sutured her prolapse back in place. She didn't make a peep, didn't struggle, and required no sedation, they all said she was one of the best behaved chickens they've ever treated.
So now we keep her in the dark like we have been to discourage further laying, and see if we can keep the sutures in for a week. Her vent already looks tons better and she was starting to pull it back in on her own, so I'm hopeful.