I like the idea of using castile paste, I may have to try that. I whipped my paste with some water to make a smooth creamy paste that would dilute easier in the future, it should work well.
I don't worry about the PH when using CP on the dogs, that has never seemed to bother them and they always smell better then when I use store bought shampoo. I just don't like how it makes my long hair dog feel rough for a couple days.