Thanks for that link gardenville. Everyone is probably different in the way burn calories and digest food and repair their bodies. Also I think your body is very likely to adapt during training and during the trip. You already have a rather lean and mean and hungry look about you. You look like you could go very far on 65 pounds. I'm sure you will collect all the data you need in training.

Like you I don't have much trouble digesting dairy based food.
What is the ratio of your diet in terms of protien/carbs/fat?

The best strategy might be to start off with the same ammount of flesh that you intend to finish with, and to hike very efficiently, many hours per day burning more fat and less carbs, which allows the diet to pack more energy per pound. I think on such an extended hike the ratio of fat to carbs should be closer to 2:1, whereas on a fastpacking hike at a less efficient but faster pace the ration might be the reverse. As protien goes I think it needs to be higher on an unsupported hike because you have to rebuild and repair your body as you go if your not going to have any binge burgers along the way. From data collect during training it's fairly easy to work out how many calories you will need, but I'm not sure how you might work out the optimal ratio. A heart rate monitor might help you figure out whether you are burning more carbs or fats, although with training I think you can burn more fat at a higher heart rate. I would err somewhat on the side of carbs though, especially with hills. On flat sections you can adjust your heart rate considerably by slowing down a little, but not so much on hills. Hills must burn a lot of carbs, especially with a heavy pack.

I presume there is data available on cummulative elevation gain for sections of the AT? Perhaps you could work out a simple formula like 50g of carbs and 50g of fat for every 1000km.kg of distance X weight; plus an additional 3g of carbs for every km.kg of cumulative elevation gain X weight; plus an additional 1g of carbs, 1g of fat, and 2g of protien for every kg of lean body mass. I'm just pulling this out of the air, but you could work out your own numbers from training. For a 40km day, with 100kg of total weight, and 1000m of cummulative elevation gain, and 50kg of lean body mass, that would work out to something like 4000km.kg of distance and 50km.kg of gain, for a total of 250g carbs + 400g fats + 100g protien = ~5000 kcal, and just under 2 pounds in total weight including moisture and fibre. Not an exact science, but training data and experience listening to your own body would help create your own formula. I think finding a comfortable efficient pace and maximizing hours per day, within reason, might be key to maximizing your fuel economy. Over many days you still need lots of sleep and recovery time though. Perhaps 10 hours of sleep per day might be key. Not sure.