I am looking to do the same thing as well, maily for washing hands etc. I use these when I travel but they are a little hard to use and pour at the same time. They hold 6 gallon though and hold up pretty well, they also fit well in front of my dog box.
I have seen those or jugs that are similar that come with a spout and a small cap on the opposite side of the handle you crack open for air.
I guess it wouldnt be as handy to fit on a wheeler, but for my bird dogs, I just carry a 5 gallon Igloo water can in my truck for all things mentioned, including watering myself.
