When I was 12, I went to a great religious school. It was at a reform congregation, and it was one that took seriously the idea that obeying all the mitzvot in the Torah was one way to do Judaism, but that probably as a young reform Jew, you were going to scrutinize the mitzvot and come to your own conclusions. I think it's a beautiful way to pass down religion if you're gonna do that kind of thing - be thorough, but have no judgement or expectations.
I knew what mezuzahs were, we had one on the doorposts of our house to the outside, as per the Veyahavtah. What I learned at 12 from Naomi the b'nei mitzvah instructor (who also broke down kashrut law and why it was there, or what all the strictures for YK were, all kinds of stuff, she was amazing) was that custom has it that that line "inscribe them on the doorposts of your house and on your gates" meant that you had to have one mezuzah on the frame of each door in your home. You touch it when you enter that room and then kiss your hand. Except the bathroom, don't put one there.
Diligent rule follower that I was, I found an unused mezuzah (or was gifted one?) and put it up on the door to my room. I also cheekily thought: if G-d [this is in the mindframe of then, I have no problem typing God now, I'm an atheist] doesn't want to be paid tribute to whenever someone enters the bathroom, I'm happy to fill that vacuum. Pay tribute to me and I will deliver you to the throne that you seek!
First thought is, I mean yeah if your hygiene game is medieval, kissing your hand after wiping your ass with it is not a great idea. Good call on not mandating mezuzahs for bathrooms.
Second thought is that this sort of has come to pass in a gentle and local way. People who know that I've written this blog for 9+ years tend to direct their thoughts about feces my way, will text me when something notable happens, will introduce me this way (never my favorite thing to have someone know about me off the bat, but at the same time, why not?), will respond with knowing glances when I come back after a time interval that corresponds to shitting.
I mean, I don't want to have any actual dominion, but I'd like to think I've honored the sentiment of 12 year old me in religious school.