The area the decal is applied to is a small, flat square, that is mapped to recieve a texture. To resize the area, youd have to redo this 3d model, and import it again to all conning towers.
I knew full well people would run out of area. As a suggestion, you could make a 5 count flag. Say, a jap flag with a big 5 on it to represent 5 merchants to save space. Kinda like hash marks.
edit:
Or instead of a arabic 5, use a roman number five. V, almost like a double pun, V for 5 and V for victory.
Probably would come out better on the texture too.