Dogs lose more water than electrolytes, and if you feed an hour after workout, you lose an optimal window for the reuptake of glycogen. Adding some pedialyte probably isn't a bad idea, but I would have to look more into what electrolytes dogs lose in order to formulate a plan of action for that.
I have never measured a dog's weight to the ounce before or after as I don't have a digital scale. I have measured dogs weight before/after though in 1/4lb increments. The hardest working dog I've ever had lost 3lbs during each workout at the peak point of his keep. He was a 40lb dog. He was getting 40oz of water, and he was getting more than 2lbs of feed everyday at that point.
Dogs in a keep, or at any time, won't drink enough water, on their own, to keep themselves properly hydrated. They drink to satiate thirst not to stay properly hydrated, and there is a big difference between the two. I personally don't know if all the water in their meal is optimal or not. I do know it works better than just allowing the dog to drink on it's own when it gets ready. There are too many variables to go along with that.
R2L, if you're going to split the water, the dog is going to need more than the allotted 40% after the work as that is when he's going to need the water the most. He's not going to need it the most 12 hours later. Maybe I'll try that next time to see how it all works out, though I don't think it will make any significant or noticeable difference.