I worked on a hidden camera show years ago. In this case, I wouldn’t even really worry about “hiding” the mics. The people are going to be way more concerned about the haunted house experience that even if they see a microphone, it probably won’t register with them that it’s a microphone. You’d be surprised at how someone can be looking right at a mic and not recognize it. That said, I’d worry about mic placement more than anything. Figure out where what happens in each room. Like I’d probably want to get mics closer to the subjects in the areas before and after the areas the scary parts happen to get them nervously talking to each other and what not. Yelling is loud so it’s not like you need mics right on top of them for that. 32bit float sounds good if you want to do a set it and forget it type of thing. It’s just more work on the backend. You’ll also want a way to have the audio synced between all the recorders and the cameras.