Although your system is decent.... and I'll likely do that if I can't think of anything else.... ugh....
So far things proposed:
D3: Too powerful
Single re-rolls hits: Decent, although kinda weird
Pulsar: Decent... but weird for the same reasons
Increasing LBs: Would likely have apocalyptic consequences!
Minimum of one attack: Boring, and still weird
Single +1 to hit: Very weird... and potential limiting.
D2: Perfect, but people don't like rolling D2s 
Oh then RC's D6-2, but that just makes bombers better against most targets, and you might as well just go with D2's.
The current average attacks is 1.67 per surviving bomber against T2.
D3 do an average of 2, and are therefore a buff.
+1, Re-rolls and pulsar all feel contrived.
D2s are weird for never being explicitly used anywhere else, and cut bomber effectiveness by 10% (I don't agree a nerf is necessary).
Increasing LBs would indeed be apocalyptic.
True Turret Suppression: Could work, but increases dependency on fighters, which is a negative as ABs get no similar bonus.
Minimum of one attack: Is more powerful against all turreted targets. Has the same average as D3 against T2.
D6-2Has an identically equal average against T2. Would go to D6-1 for crippled targets, which is again the same as now for T2 targets.
D6-2 with modifiers Similar to D6-2, but also incorporates True Turret Suppression and defensive bonuses for turret massing. Starts to get complicated, would actually affect tactics to a great degree, and still doesn't benefit
Of all these systems, the only ones I would consider viable are TTS or D6-2, with a preference for D6-2, for the simple reason that they change things the least and don't adjust the overall power level of bombers that much all things considered. Of those two, D6-2 is the simpler and doesn't arbitrarily favour escorting bombers over escorting assault boats.
The only other system I can think of is a bit more radical:
Bombers get D3 attacks. They are therefore 20% more powerful than at present against T2. Fighters get 1 attack each. Including fighters in a wave therefore dilutes their effectiveness - a wave of half bombers/half fighters would score 1.5 attacks on average, which is less than a wave of pure bombers at present. Fighters also count as resilient against attack craft markers, but NOT against turrets, torpedos or direct fire weaponry. Resiliency is changed so that multiple saves may be attempted per turn. Fighters must engage each other before moving on to attack the bombers.
How this would play out is: A wave of 2 Fighters and 4 bombers are intercepted by 3 fighters. The interceptors fail one of the 2 saves caused by the 2 defending fighters, and simultaneously the defenders fail one of the 3 saves by the three interceptors. In the second round of combat, the remaining defender fails its saves, and so does one of the attackers. In the third round, the remaining attacker removes one bomber and passes its save, and in the fourth round, one bomber is removed and the fighter fails its save. 2 bombers remain and may attack a ship.
This gets around Sigoroth's earlier objection to a 2:1 kill ratio, because a fighter is just as likely to kill as many bombers if they contact all at once, or if they detatch and contact one-by-one.
This sounds good, but would probably require play testing. Also, a fleet without any ordnance would be much more vulnerable than one that could put up SOME defensive ordnance.
