Not sure what would be considered fighting, but troops could make a bomb sub, being that one troop normally carried enough to take out a building. So maybe dropping troops on a town could have the effect of 1 troop=1building.
Cause once you even consider the thought of letting troops actually fight, then people will start crying about how they do shoot on planes from the back of lvts and m3s. The troop per building effect would require lil change as opposed to the fighting soldier.