Dr. Bronner's has worked well for us humans in the past. Haven't used it in a while but we liked it when we did. At home we use Aroma Paws for the benefit of the dog's coat and skin. That would be my first concern about bathing animals "on the trail". Unless a dog gets into something really nasty (deal fish, Skunk, etc.) their coats will usually protect their skin and all you should need to do is clean the outside of the coat. A good brush and some quality time together can work wonders there. A light mix of a good shampoo like Aroma Paws or the Dr. Bronner's can be used for a "sponge bath" for the affected areas if more is needed.
My dogs and I still hike, although I can't do what we used to do. We can stay out all day on state park type trails, though, and my guys are still fine when we get home. No bath needed. I bathe mine maybe three times a year. And I just do that when the Holter comes off the Boxer and I need to clean the solvent off his coat. I do all of them just so they're done.
