Screw medieval times, I grew up using the bushes. I used to voluntarily live rough in the woods for up to a month at a time. All I would take with me is my .410, a hatchet, and a survival knife. I could purify my own water, hunt and fish for my food, build my own shelters, make fire with 2 pieces of flint, and more. So when I say "live rough" I mean ROUGH.
Also if I'm out driving outside town and suddenly have to go, I'll pull over and drop my pants right there.