So i was pondering the idea of how to keep ones Star ports up longer if say 'Darca' shows up with a 3 ship fleet of precursor gunships....

In Gal Civ II there was a path on the tree only for fortifying your starbases. Near the end of the line if you outfitted your starbases with enough constructor rings/add ons, your starbase could be virtually impervious to even the most powerful fleets. I remember getting attack values of 133-133-133 and defense ones of 93-93-93 about 2/3rds up the tree. Many mods allowed this kind of strength early in the game and it created a galaxy where you avoided starbases as they were just too tough to destroy. 

Another solution is to get a tech line called Star base/port fortification. It equips the base/port with attack & defensive stats earlier than you could possibly get for your actual ships. A constructor or two and viola your precious star port is bristling with 12-12-12 attack and 20-20-20 defense. Now, this would make it HARD to destroy such ports but not impossible, in fact it would be a fun challenge to go and wear its hit points down with waves of fleets. 

Must prepare for Darca's fleets of death........