I love the thinking outside the box. For 8 bucks its worth a shot just for the fun factor!!
Was trying to decide if i would like something like this. Could easily simulate to do a test. Put a rag on the shower floor and try taking a shower where you have to have one foot on the rag anytime the water is running. I sorta spin around (like a beautiful ballerina) to rinse off soap. Sometimes facing forward, sometimes backward. The foot pedal might make it a pain just to keep the water running.
A locking foot pedal like a golf cart brake pedal might be another fun idea. Waw-waw pedal for when you have music blasting during your shower?