If I am out for that long I take a couple of plastic tubbed salads made up of a variety of ingredients. My favourite at the moment includes sliced boiled eggs, tomatoes, bacon and avocado. I also pack nuts or trail mix, jerky, fruit and maybe a boiled egg or two. You need to have the salads chilled but it's no prob. if you are in the car. Enough food for 12 hours or more.