How about this for a handy scorched earth rule?
For any unit that would hit in any round of combat on a land territory, you may instead choose to apply that unit’s # of dice pips worth of damage to any facility in that territory (whether you control that territory or not).
Okay, some examples.
Infantry (on attack) hits with a 1: target facility gets 1 damage counter.
Tank (on defence or attack) hits with a 2: target facility gets 2 damage counters.
Fighter (on defence) hits with a 4: target facility gets 4 damage counters (no AA defence because you control the AA guns).
Fighter (on attack) hits with a 3: target facility rolls AA defence. If AA hits the fighter, it is destroyed and the facility takes no damage counters. If AA fails, the fighter survives and the facility gets 3 damage counters.
This also allows some strategic damage to be inflicted to enemy facilities on land (via strafing) without risking one’s bombers… Thoughts?