I do asphalt work on residential properties. Generally I try to find a bathroom but sometimes if it comes up I'll squat beside the vehicle on a country road. If there's no bathroom anywhere nearby then I'll hop in the back because the windows are tinted and piss in an empty coffee cup. If I can pour it out discreetly right away I do that but if not it sits in the cupholder until it can get dumped. Hubby has it a bit easier but generally does similar except he'll stand just inside the door to piss in a cup - I like that because I get to watch.
