Pound cake sounds great, especially if made from the old recipe (pound of butter, pound of flour, pound of eggs, pound of sugar) as opposed to the wimpy substitute sold in stores. Here's another idea to consider, especially with December only three months away.
Consider the much-maligned Christmas fruit cake. It has lots of eggs (protein), nuts (protein, fiber and healthy fats), butter (unhealthy fat, but you are, after all, hiking all day), fruit (carbs and fiber), flour (carbs) and the inevitable sugar. Many of us get too much of it as presents from somebody or other, and a lot of it gets tossed the day after Christmas if not sooner.
Instead of tossing the leftover fruit cake, why not slice it and freeze it to use for backpacking trips? Wrapping it in cheesecloth soaked with whiskey/rum/other alcoholic beverage makes it keep a lot longer and taste a lot better. However, if you do that you might want to have the fruit cake for dinner instead of breakfast!