I'm going to say 7 as my absolute max for people sleeping over. I have 2 sofas and a futon, plus a space in my room in a double bed. Everyone else would have to sleep on the floor.
I will have to check on what my housemates are up to and confirm they're cool with me inviting over a bunch of weirdos from the internet , but they should be cool with it.
You would be more than welcome, Danny.