Kevin - I don’t want to rain on a good adventure, but presuming your mileage is correct, the hike you propose is certainly doable for an experienced long-distance hiker but highly unlikely for a occasional backpacker. If your game nonetheless, good for you. I would read up on ultra-like hiking techniques (don’t forget to pack a rainjacket, shelter of some sort, water treatment, headlamp, water storage, pack cover, etc?). I would start doing a lot of walking to get in trailshape (jogging, swimming, lifting weights, etc. are all fine and good but nothing but walking gets the little things like the soles of your feet, heels, toes, knees, hips, etc. prepared for the pounding they’ll take 12 hours a day/8 days in a row). Evaluate your food needs in light of the work you’ll be putting in (the preliminary diet you propose wouldn’t begin to satisfy my fuel requirements on the trail). And come up with a plan B should you fall short of your ultimate end point. As for water, don’t sweat it too much. Water is plentiful on the AT most years. You’ll find it every 5 miles or so in the southeast. Good Luck!!
Matt