I have a simple house rule idea for limiting bombers air blitzing abilities. Purpose of strategic bombers is
A) to attack enemy infrastructure and thus damage enemy’s economic production and/or morale.
B) to soften enemy’s defensive positions in preparation before a land attack.
But strategic bombers have not been used to kill enemy units directly, at least not in significant numbers. The purpose A) in Global’40 is modeled via strategic bombing rules. Purpose B) is modeled by bombers participating in regular attacks. If you think about it, purpose B) is very similar to naval bombardment. As there is clearly no advantage of supporting amphibious landing of 1 transport with 12 cruisers (and OOB rules nicely model for this by limiting the max number of bombarding warships), there clearly shall not be much difference in a land attack of 2 inf supported by 12 bombers and 2 inf supported by 2 bombers.
So the suggested house rule is: Attacker may bring at most as many strategic bombers into an attack as many land units he has brought or in a case of a naval battle as many warships (including subs) he has brought.
This house rule shall have almost no impact on conventional strategies*****. It will only start to matter with stacks of bombers. Suddenly one cannot simply deter Allied fleet off Gibraltar with tons of bombers, one cannot simply keep Normandy safe by 15+ bombers and 3 mechs in W Germany. One cannot threaten air-blitz of London,Cairo,Moscow, and Gibraltar by simply stacking bombers to Rome. Germany will have to think how to bring land and naval units into its battles. Allies in Europe will be able to move small armies around not worried about being killed by 1 mech and 10 bombers.
Also with this HR one can still possibly try to stack bombers, bomber stack shall still work fine against Moscow as Germany has tons of land units on that front. But defense of western front will be much harder.
*****The impact on conventional strategies is that it would not allow clearing blockers and lone TT’s with bombers only. It would also make unusable “German bombers in Pacific” strategy. If one wants these still to be part of the game, then the house rule can be modified that a single bomber is allowed to participate in any battle regardless of what other units participate. Nice advantage of this rule is that it does not require any modifications to tripleA. Players just have to watch for not violating the rule.
EDIT: As per follow-up discussion I implemented the house rule such that bombers attack @ 0 but if paired 1:1 with any land units or warships (excluding carriers) they get +4 bonus to attack.