I think it would be very cool if we could customize the shield loadout directly, as currently can be done with weapon systems. (shields would have "generator" points to manage their loadout. Some of the ordinance modifications would need to be shifted over to the generator loadouts.)
I would have several kinds of options available under two headings: Core Shields and Shield Mods
Core Shields:
This determines what shield type the ship is using, Fixed or Omni. The core shield slot would be one hardpoint; the shields you could fit there would be dependent on your generator capacity and ship size.
Omni shields would be more powerful, sporting better damage:flux ratios and fuction just as they do now.
Fixed shields would cover a very wide angle, have worse damage:flux ratios, and would be slightly more expensive in generator usage.
Shield Mods:
Here is where there would actually be differences from the current game.
Directional shields: Shields like the OP suggested. They would be pre-tuned to a specific shield arc and would not turn regardless of the core shield type. They would also use generator resources and
could not be activated or deactivated independently.
Directional shield radius would be slightly smaller than that of an OMNI shield, so if your core OMNI shield were covering the same arc, it would take the hit rather than the direction shield.
The number of Directional shields you could have would be limited only by the available hardpoints and shield generator resources on a given ship.
Auxiliary Generators:
Provides additional shield resources. (Increase generator point cap) This would allow stronger Core shields to be mounted, or additional shield mods.
Directed Flux Buffer:
Improves the damage:flux ratio for a specific damage type while taking a slight penalty to other types. Only one type of these could be mounted on a ship, though you could have more than one of the same type. I.E., you could make you shields much stronger against kenetic damage, while being more vulnerable to the other types of damage.
Just a few thoughts anyway