OK, would you then allow any fighter to have this Promotion as a part of their xp progression (which would make Naval Fighters less highly promoted for normal Air Operations than others) or would you attach this promotion to a new unit "Naval Fighter" as a free promo, but then change the Strength, Range, or Cost of the unit vis a vis "Fighter" units?
As long as we are at it, might as well mention a "See Submarines" promotion, only available to Bombers (and Airships, which would get it free?) to make ASW aircraft... what do you think?