Here is an mobile dish washing station that would be perfect for camping. You can also make the frame from PVC pipe (tubing) pieces and you can still take it apart and reassemble it upon location.
Here is a hint that makes washing dishes easier, immediately after dishing up the meal onto the plates put two pots of water on your heating source (campfire or camp stove) to boil while you are eating. When your done eating, your water will be heated and dishes can be done before leftover food dries on dishes.
Click here to read how make this mobile dish washing station from Ultimate Angling website: