I don't know why fruit cake isn't promoted more as a hiking food. It's extremely nourishing, especially if you leave out the commercial candied fruit with its dyes and high fructose corn syrup (gag). Best to use many varieties of just plain dried fruit, which I always soaked in booze overnight.
To resurrect dried out fruitcake, take some cheesecloth, soak it in brandy/rum/bourbon (your choice), wrap dripping cheesecloth around fruitcake, cover with plastic wrap, let it sit 6-8 weeks. i did this back in the days when I baked my own fruitcake. Of course that meant baking the fruitcake in early November and hiding it from the rest of the family (especially the teenage boys!).
Although most of the alcohol is gone after 6 weeks or so, it's still not recommended to eat large amounts before driving!