First off, I no longer use "cubes," I use the little very low sodium bullion packets from Herb-Ox (unless I am putting together a "vegetarian" kit). These have the advantage of being sealed in foil, dissolve much quicker than the cubes, almost instantly, and are much, much lower salt. Vacuum packing the bullion, especially if cubes, is the way to go.

The bullion gives you a very compact means of providing a welcome morale boosting hot drink which stores well.