Seems ironic to think of fruitcake as "lite food"!
Most commercial fruitcakes really are beyond eating. I have made my own for many years using my mother's recipe. However, that was complicated and long. I now use the recipe presented by Alton Brown of the Food Network who gives a brilliantly simple but moist and tasty recipe (search alton brown fruit cake on foodtv.com) which can only be improved by soaking with a little rum (or brandy if you're posh). It'll keep you hiking for hours. The rum butter would obviously improve it, but difficult to stop going rancid on a summer hike.