I've only ever taken my dog on short trips...usually overnight 20 to 25 mile trips. The most he has ever done is 40 miles. He usually eats the same thing I'm eating. Probably not the best or healthiest way to go but it is the easiest and I figure its not going to hurt him to eat human food for a day once in awhile. But now I'm planning a 100+ mile trip and that plan probably isn't going to work for that. It won't be on the AT and resupply will be very limited so this is going to have to be planned out pretty carefully as there won't be much room to make adjustments.
Do you offer your dog food and water every time you stop for lunch and for a snack? I usually do, but like I said, its human food and I'm wanting to get away from that on this trip.