My wife was my PALS.
When we couldn't find a family or handicapped restroom, I would simply and boldly accompany my wife and her PWC to the lady's room where I would lift her onto the toilet, clean her bottom, wash our hands and thank everybody for their understanding as we rolled out the door. Everybody seemed to understand.
Of course, you're probably thinking that you'd feel more comfortable in the men's room. But most travelers are men (truckers) and they're more likely to be either more vocal or even try to assist, which might be uncomfortable. So I'm thinking the lady's room might be more accepting. Let us know how it goes. --Mike