Not a cyclist, just here from “All” on a slow Friday afternoon. But I am a country boy.
If it’s just piss, hang brain wherever there is some seclusion. Ain’t no one gonna care, unless you’re pissing on someone’s lawn that is.
If you have to shit, well that’s a different story. Shit before you go is the best strategy. But in cases of emergency, find a bush with a tree trunk you can grab onto and let ‘er rip. Leaves or a clean stick will deal with most of the nasty, but it might be good to keep a tissue or two in the fanny pack.
Bear in mind no one wants to see you shitting in the wild. Seclusion is much more important in this case.