The public bathroom

I have a problem. That is a little girl almost 3, and a son almost one. Of course they are so much fun and bring copious amounts of joy to my life, when it's just them and me things can get difficult. For example, Gwen is now potty trained. But that also means that when she says she needs to go, I've got to start looking for a bathroom pronto squanto! But picture this scenerio. In the grocery store, cart full of food and my two offspring, Gwen says she needs to go. We head to the bathroom where I have to get the kids and my purse out of the cart because I can't take a cart full of merchandise into the bathroom. So we head to the handicap stall so there's room for the three of us in there. No baby changing table in the stall, so I have to hold Drake (since he's not walking/standing) while I cover the toilet seat with scads of toilet paper so Gwen's little bum doesn't touch a public toilet, then gently set her on top of it so it doesn't fall in the toilet, wipe her and help her down, all one handed. Then while she's pulling up her pants, I realize I really need to go too. But I've done this before, I can totally hold Drake, hover and then re-dress myself one handed. But oh no, Gwen's DONE! Despite my instructions to keep the door shut, mommy's not dressed yet, Gwen's opening the stall door. Of course this is also the same time that all the women in the other stalls are now out buzzing around our stall. I quickly am trying to pull up my pants, balance my purse and Drake, and can't figure why my pants are not up yet. Of course, Drake's foot is in the way, keeping my pants down. Oh the humiliation. People have asked, "And none of the women out there helped you?". But I figure they thought it was better to pretend they didn't see, and pretend they didn't know what was going on. Oh they saw. They knew. But how do I change this sequence of events? Because guess what? It happened again, the very next day at Costco!