There are, believe it or not, funnels designed to help women pee standing up. I read about them in a story about a quartermaster [US Army supply officer] in Iraq (no bushes, no trees) ordered a crate of them so her female truck drivers could just pee on the side of a truck tire along with the male drivers. (No, I don't know why Army drivers pee against their tires. I was in the Navy.)

I ordered a box for my wife after she expressed some hesitation about going on a road trip with the questionable women's facilities along the route. Alas, years later, she never actually found herself desperate enough to try using them.

Search for "PeeBuddy" on Amazon.