If you have to go, well nature calls. I don't see the big deal being unprofessional here. Yeah if you do lawn work in the inner city and pee in the customer's front yard then that's just stupid.
I do ask customer's to use their bathroom from time to time, maybe 2-3 times a year. But I'm not carrying a bottle or bucket in my truck / trailer to pee in, it will get spilled or turned over and I'm going to be pissed (probably at one of my guys). Do what you have to do- indoors or outdoors.
We ride Hustlers and stand on Exmarks.
Stihl and Redmax Handhelds