Adjusting the unit cost for "huge" makes sense...I think. Unless I'm sorely mistaken, units cost is the same in "large" as they do in the unit stats file which is set up medium size units. I suppose "huge" would do the same.

I'm busily invading Gaul again in yet a new campaign, and it has stacks of simple warbands. I can see why though, that is all it can build in the cities I've hit so far. I faced a couple of swordsmen units in the first big army, but the next several have all been base level with perhaps a unit of cav.

Another way to approach it with huge might be using 2 turn builds. That would reduce the depletion of population at the start of a campaign. At least it will give the buildings a chance to get upgraded before the population is depleted.

I've modded so that there won't be any more war dogs or head hurlers being built.