@Dirkules , we're both using the black opaque Garcia 'Backpackers Cache' that some National Parks (Olympic & Tetons) rent out. It's about 610 cubic inches; a couple of my buddies use the blue transparent Bear Vault 500, and they like it. The Garcia weighs more, and if you're one of those who tries to cut every surplus ounce here & there, its heavier weight is a consideration.
You might fit 2x4days of food into one container (maybe not the BV450 though), depending on how much you eat and how efficiently dense the foods you choose are. I have high caloric needs because of my metabolism, my buddies who backpack with me bring less food than I do even though they are bigger dudes than I am. (Like I said, on the same trip, a BV500 works for them when I'm barely cutting it with 610 cubic inches.)
Many of the freeze-dried meals you buy can be repackaged with a vacuum-sealer to take up less space; you can pre-crush them a bit more too to make them more condensed. We use finely ground oatmeal for breakfast, and those vacuum sealed packs can be manipulated to fit into gaps, so that we have as little 'dead-air' space in the containers. Believe me, when we're packed, they are packed TIGHT. If you are going to use containers regularly for long trips, I think it is worth practicing packing food to get your system down pat. We also make our own pemmican that is quite malleable (in vacuum-sealed envelopes obviously), and have those shaped to fit gaps too.
Remember, you first day's lunch & on-trail snacks -- dinner too -- probably don't need to be in the container when you start out, so you save that space. That's food that will be eaten and gone before you 'use' the container for your first overnight. That helps. (But remember to save enough room for the garbage that could smell from the first day.)
Good luck! Hope it works out for you!