I used one of those collapsible nylon bowls, but it was hard to clean and always collapsed at the wrong time, inevitably miles from water when carried water supplies were runing low. It finally got chewed up! After that I used a Ziploc plastic bowl. It's flexible, cleans easily and fits nicely in a dog pack around a plastic bag of dog kibble.
I used just one bowl, for both food and water.
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey