We use our foodsaver and do some prep work first. We freeze in marinade chicken breasts, we buy bulk hamburger from our butcher and then we freeze them very flat in the the foodsaver bags (they defrost quick then). We also premake burgers and foodsaver them. We marinade a tritip or two, and the becomes dinner one night and leftovers for tacos or sandwiches the next. We take lunch meat, hot dogs, sausages, eggs, etc...
The hardest part for us is veggies, we love a salad and obviously that can't last forever, so we end up buying a head of lettuce at an expensive market if we can.
When you are in Yellowstone, I would suggest a quick drive out to West Yellowstone, such a cute place and they have the Grizzly / Wolf discovery center...you could get groceries there for sure.