Part of the problem is that the ammo bunkers are nicely grouped together. On a small base, it takes just one pass with a cannon plane to take out the ords.
I think that more bunkers should be added to all fields and dispersed all around the field, forcing the single porker to have to make multiple passes to take out the ords. This would allow some sort of defense against the porker, and if a defense cannot be formed quick enough, the auto-ack should make the task difficult at best.
If a side wants to take out the ords at any airfield, it should require a concerted effort of multiple aircraft to accomplish the task. When 1 plane can disable any strat so easily ... something is wrong.