To get through any day when I will not have access to a private clean restroom (say a day-trip by public transit) I will stop eating after an early supper the day before. I'll carry a protein bar to eat if I get lightheaded or crazy hungry, but the less in the less out. I do drink plain water or tea during this time.
I also limit my food during regular workdays, eating just very small amount mid-morning, and then my largest meal the minute I get home from work. I work out at lunchtime, and can usually manage with just one bathroom trip.
Finally, I try to schedule all my outdoor running workouts for first thing in the morning on weekends/days off so I can run before I eat anything. I will drink some water first, or half a cup of tea if I want it. Once I'm done with my workout I get to eat more often on weekends/days off when I am home.
So yes, I've naturally fasting for between 14 and 20+ hours as a way to keep my life as normal as possible. The main downside is I do end up waking up at night to go. If I could eat my meal at midday that would be better, but just does not fit into my work schedule.