Well, in certain maps such as Midway, all bases have an entrance. All you have to do is build an extra starbase, build 3 Defense turrets and a Tavara class ship. You might think that I am insane, but I am not, really, it works very well against small to medium assaults, if you have a very large invasion, you just have to send 10 more Rhienns to the defense perimiter. And the Tavaras are a bit more tougher than you think.. I had 2 Negh'Vars, 3 K'Vorts on a Tavara's tail, I was retreating, and I thought, "Great, a Tavara is lost, the last thing I want to see in this game" on the contrary, it survived the long way and its shields were down to 19%, by the time it reached the base that is.  

It works fine even with AI Hards, but I dunno about real players..

wow