I doubt any of the people answering above me have ever been on a ride of such distance. Trail mix is a snack not a meal. If you will be camping you will need to bring a compact camp stove and canned or dry meals. Boil water and make pasta. Eat plastic packaged tuna and salmon for protein. Peanut butter. Pick up fresh fruit at stops.
Other than that bring money and eat a big breakfast at IHOP or some such. A trip like you are planning burns a ton of calories, and if you don't replace them your body will cannibalize your muscle tissue. Talk to cross country riders or read their blogs. Most eat eggs, bacon, pancakes, bananas, potatoes, orange juice, and coffee -- just for breakfast.
The direct route is 903 miles and by bike it will be longer. If you are lucky and totally bicycle fit that is a two week trip. Some mountain pass climbs can be one day alone, therefore the possibility of being closer to 3 weeks possible. Always carry what you will consume in 2 days, and replenish as you deplete. I would suggest training rides with weighted panniers on your bike (like 60 lbs if you are camping). If you haven't started training -- get going. You will need 2000 training miles to make this trip.