Chaturbate is pretty good for this. I've actually heard quite a few women pee while on cam. Of course, it's in the background and most of the time they are new broadcasters. A lot of them will mention they'll brb and sometimes actually announce they're going pee. Really it's just a matter of luck - being there at the right time and place. But also being consistent and waiting for your favorite model to go.
One of my favorite ones was a dark-haired woman in her mid-late 30's and had big natural tits. I believe she was a little tipsy on wine or something, but when she peed, you could h