I'm having to relisten to book 5, was on chapter 62, because there's mention of Carl forming a corporation and I cannot for the life of me remember that happening... Anyone able to either point me to the chapter it happens or give me a brief rundown of how it happened?

I don't know the exact place in the book, but isn't this Donut stealth organizing the Princess Posse outside the dungeon to buy

Princess Donut is communicating with the official fanclub, the Princess Posse, and they're chartering as a NFC (not-for-conquest) organization.

Carl meets his lawyer, Quazar (favorite character, me) for the first time and has him filing a bunch of legal matters outside the crawl, including liasing with the Princess Posse. There will be more about this in a later book, but so far it's almost all been off-screen.