Chances are that you ladies are smart enough not to do this, but in case desperate times call for desperate measures, let me warn you:
Don't try to take a carseat into a non-handicap public restroom stall.
I was at the Wal-Mart when suddenly I reeeeally needed to pee. Of course the restroom was busy and the handicap stall was occupied, so I waited. And waited. And waited.
Deciding that the damn woman must have fallen asleep in there, and about ready to piss my pants, I headed for the nearest open stall. The door opened inward, so I had to hold C's carseat over the toilet to get the door shut behind me.
Then I realized that the stall was only about 6 inches wider than the carseat, and I had to turn around. I tried to squeeze between the carseat and the wall, and while my belly squoosh is pretty forgiving, there just wasn't enough room. I tried harder, and got stuck. I literally could let go of the carseat and it wouldn't go anywhere. C thought this was great fun and started shrieking and bouncing. Holy shit, I had to pee!
I almost cried when I realize that even if I called for help, there wasn't enough room to open the door.
After about five minutes, I realized that the carseat was caught on the toilet paper dispenser. If I could lift the seat up about a foot, we'd be free and clear. I summoned arm strength that I normally don't possess, heaved the seat up to chest level, and was able to complete my turnaround.
By the time I set the carseat down, put paper on the toilet seat, and got sat down, I had peed myself a little bit.
Never again.
Re: Advice free of charge (long)
Also, noted.