Post-close update: I ended the day by locking in my mark to market profits. Tomorrow I should have around 150k in my cash account to play with, and on Monday I should have my margin buying power restored since I think I've successfully avoided the pattern day trader designation.
It probably goes without saying, but unless you're like me and you're willing to be long 500k of this stock in a brokerage account, you need to use options to actually execute this sort of market making strategy yourself. I myself left Virtu right around when we were starting to get into options, so I've never actually traded options myself. I'll learn to trade options sooner or later, but for now I'm just getting back into the game by trading the outright equity a little. Having a great time too :)