I've been using spare clear acrylic 1" hex bases under my existing figures to mark out the Big Men. It works quite nicely, as it's obvious without being glaring, if that makes sense.
I just use a dab of Blutack under the existing base (my figures are on pennies, so sub-20mm bases) to hold them onto the hex bases.
On the Big Man cards in the turn order deck, we just added notes like "Section #1, Corporal shouting" or "...corporal with fur hat" and that works OK, you just have to find a slightly different figure for each Big Man.