I find it interesting that so many people have difficulty taking care of business in public. I mean, heck. I'm just glad I don't have an audience, but if I do, I still go when I gotta go.
As far as my gun, it's one one of the things at the fore front of my brain when I'm carrying (which is pretty much always unless i'm at work because it's forbidden). The idea of forgetting my gun in a stall is laughable. I'm very aware of the weight on my hip and all that it means if the s*** hits the fan. (pun intended).
I usually use the back of the toilet or the dispenser. If neither are up to the job, than I'll lower the pants with one hand on the weapon (I carry IWB), and pull up the same way.