A few years ago I worked for a small startup using a tiny live/work loft as an office in the heart of downtown San Diego.
We had the exact same issue you describe where 7 guys and 3 gals were all terrified to use the restroom because any little sound could be heard through the wall into the main space.
Because of that we started seeking out other places to deal with nature, which led to the phrase "I'm going to visit the Hilton".
Needless to say by the end of my time working there I knew the nearby Hilton & Marriott hotels in and out, including how to act like a guest to gain access to the better restrooms (although they surely caught on).
At the time I wondered whether a crowd-sourced bathroom finder app would be feasible and purchased the domain thronehunter.com, which I still own to this day!