The bathrooms I have been in like that, having a toilet and urinal side by side no divider, they also have always had a lock on the door so you can by in there by yourself. So I lock the door and use the toilet, still trying to become comfortable using a STP without taking my jeans down to use one. This would be the place to try a STP through my unzipped jeans when I am ready to try that, noone else around to see what you are doing.