I'd say play around with it, see if doing that actually hides it from the other players.

Greetings! Apologies for not having this feature previously. Whenever me and my friends would play, we would rely on honor system to hopefully limit cheating. But, I realize that this doesn't work for everyone.

So, I did a little big more playing around in TTS and figured out how/where the drop some hidden boxes for each booklet (without it being in the way on the already crowded table). I've pushed the update the the Workshop and updated the "Notebook" appropriately with instructions on how to switch each hidden box on/off when the haunt starts.

Hopefully this solves your problem.

Happy Haunting!
-DH