What the heck does "one deck of cards and two sticks of gum" mean?
Anyway, that could be a good solution. small units are considered to be skirmished while larger units rank up and get the rank bonuses. Makes sense to me. You don't really get the benefit of ranks even after a skirmished unit goes into CC (maybe one), but if I am marching a unit of 10 Halberdiers as a detachment for a unit of Greatswords, it would be nice for them to get that -1 to shooting for being considered skirmished.
Makes sense fluff wise as well. A unit with fewer guys in it will be able to move around more easily.