Great post, Mary!
High caloric density foods:
* Fats and oils (~250calories per ounce.) Olive oil, parified butter, etc.
* Cheeses: Usually the harder types are better in a bear ball
* Jerky, dried beef, hard pepperoni, summer sausage, etc...
* Dehydrated vegies: Corn, peas, onions, green beans, okra, peppers, tomatoes, apples
* Nuts, sunflower seeds, cashews, macademia nuts, peanuts etc.
* Instant potatoes
* Oatmeal (mostly for fiber, offsetting the the above)
* 1/2 pound bisquick
* Lipton Sides, rice
* Vitamin/mineral pill to insure balance...vitamin-C can be difficult to get.
* spices (cinimon/sugar, red pepper, salt, black pepper, minced garlic, oregano)
* Chocolate bars, crushed fritoes or potatoe chips, etc.
All are repackaged into bulk baggies, with the air "sucked" out.
I can manage to get 7 days in a Bear Vault Solo. This lets me make a large variety of meals: Soups, stews, spanish rice, tacos, pot pies/shepherds pie, etc. All require 15-20 minutes to prepare. Making a bisquit ball may take longer, but this is only on days I can get a camp fire together.
Caloric intake really makes a difference: Hiking and climbing the high peaks area with 8 pounds of food is much different from paddling 35 miles. I generally need less than average. I never plan on loosing weight, I just do. But, I carry a 10-20 pound "reserve", so it doesn't really bother me to head out with ~3000C per day. However, for LONG trips(2-3 weeks) I plan on more food.
I think 2/3pound per day would NOT be enough. Mike Clelland's book mentions his eating schedule. Lower for the first week, normal the second week, much higher thereafter. Well laid out amd written. I agree, based on my experience. Though I usually "settle in" within the first 3-4 days. (I believe this depends on how much time you have spent in the woods, too. About the second time I have to crap, my system is pretty much aclimitized to being out, and, I am eating more.)
I am not sure if you could do 21 days with any bear ball. Figuring a pound of food per day (this is light) this is ~23 pounds of food. The Berikade Expidition would be the only candidate, based on size. This would be close. Resupply stops always cost about a day of hiking, if they are not on the trail. So, I try to avoid them, but I think you will need at least one. Generally a bandana bath near any water will keep you clean enough. Carrying enough water could be the big problem with the pack weight of 35pounds, though. Again, with proper planning, you can probably do this with one resupply near the middle with no discomfort.