It's a good question... I've never gone the everclear route--usually just use high proof bourbons for lightweight trail alcohol.
However, thinking truly UL, my first thought would be that you could do a lot by infusing the everclear BEFORE you hit the trail... pour half a bottle in a mason jar with some citrus peels or ginger root or peppers or fresh herbs... let it infuse for a day or two, strain it through a cheese cloth or coffee filter, and see what you've got.
I can't think of any reason you couldn't use citus-pepper everclear as a stove fuel (might even smell good cooking), and would give you an edge up on your cocktails.
Another thought would be to look into some of the other powders. Apple cider powder and hot chocolate powder are common, and could give you some good options. Apple cider powder and everclear=hard cider. Drop in a cinnamon red-hot or two and you'd have a spicy, tangy drink.
Hot chocolate (or chai tea) and a little creamer would go a long way with the everclear.
And, of course, don't discount the possibilities of Kool-Aid powders. It'll be more like college punch than gourmet cocktails, but will still be tasty; probably worth looking through that section at the grocery to see what some of the options are these days.
Last thought (and probably the best, if you're thinking gourmet cocktails)--it's not really that heavy to carry a second, tiny bottle of some juice or oil for adding to the everclear. Fresh squeezed ginger root, for instance, is incredibly strong--very little needed to impart an intense ginger flavor. A tiny squeeze bottle of fresh ginger juice, some lime electrolyte powder, a little sugar, a little water and everclear and you'd probably have a rocking cocktail.
Oh, one more thought... Essential oils. Mint or grapefruit essential oil, for instance -- intense flavor and could fit in a tiny, tiny dropper. Bitters aren't as concentrated as essential oils, but could also work well and are portable in very small quantities.