I think (with my proposal) with your proposal in mind (I read yours a couple of years ago and it stayed in mind) would be:
Mega: Line Ship (no ewar bonus)
Hyp: Scram Bonus
Domi: Damp Bonus
Even though my OP gives the Mega the Damp Bonus. If the mega got the Damp bonus it would need a serious reduction of firepower as a consequence. In this setting we make the Domi the Line Ship.
However you’re original suggestion also works:
Hyp: Damp Bonus (to force other BB’s into close range)
Mega: Line Ship
Domi: Scram bonus.
I’d like to hear your input overall though. I also agree that Gallente is the most difficult race to balance. Being forced to engage a Hyp in grapple range is nutzo! lol. That’s why I prefer the Damps on the Mega.