I stopped at my local Kwik Trip this morning to get gas and use the men's room. I found, to my surprise, that they have installed a handy flip-down gun shelf in the stall. It is right within arm's reach while one is sitting on the pot. I was able to flip down the shelf, unsnap my IWB holster and set my rig on it while I went about my business. It's much better than trying to set my gun on the tank behind me, laying it on the floor, or hanging it by the trigger guard from the stall door hook.
Apparently the shelf also has a secondary use as a child seat and restraint. At least that's how it's labeled...