Reading through a few post it occured to me we'd never done a defensive wolfpack type SA for bombers.
Example : MASS RAID: If this aircrafts local sector contains another aircraft with the mass raid special ability. This unit has +1 armour when attacked by ship anti-aircraft.
Further thinking on it it may even work better in the form of a more general house rule. Where groups of identical bombers, or destroyers and auxiliaries get a boost to a minimum threshold of say 5 armour or 5 ships aa within a sector.