Cutting a bath in half and making room to panic.

I am on a bit of a cost cutting kick as I want to keep this project as manageable as possible. The plan had been for the main house to have three full baths – master, kids’ suite, and mudroom. Well, with the wife’s approval I have removed the tub from the mud room bath. My original idea was to have a full bath where very dirty people could clean up without tracking all through the house. But this will save about a thousand bucks and I feel like people (mainly me) can just remove their clothes before going to one of the other bathrooms. So, I now have an extra five foot by five foot space to mess with. I am thinking to make a hidden room. It would be accessible through the master closet. Why this craziness, you ask. Well, for starters this really appeals to my inner child. I just don’t think it gets much cooler than a secret room. Also, while I have always been a bit paranoid, I think it is increasing as I age. So I am liking the thought of a secure, hidden space for my family. I’m not sure how I would disguise the door, although there are several options. This brilliant idea just came to me, so it will need some refining, but I’m pretty excited.