Something to help fill out the Defense tech trees:
Improved Targeting Computers: Golan Space Defense Platforms can target 2 / 3 ships at a time.
Quad-Laser Batteries: All levels of Golan Space Defense Platforms gain a battery of mid-range point-defense lasers.
Shielded Stations: All Golan Space Defense Platforms gain energy shields. (should they just have these without requiring research? Most combat-rated things in Star Wars do, barring TIE fighters...)
Invasion Protocols / Planetary Shields: Preparing for enemy invasions increases the likelihood of surviving them. All planets take 5% / 10% / 15% reduced bombing damage from enemy ships.