I would go with something like:
Modification:
6 Pts
Enhanced Laser Boosters
Unique
2 or Less Attack Ships Only
Gain +1 Attack Die
Pricey, but Dash Rendar with a 5 dice HLC turret?
You forgot the primary weapon only limiter.
.
Also what about ships like backstabber? Can you imagine a 22 point BS getting behind you at range 1 and shooting 5 attack dice??