Defending against Cruel AI

I've been going at it with the Cruel AI for awhile now, and I'm starting to get used to them, but I'm still having trouble figuring out the best way to defend against them.  If there is a single choke point, I will win most of the time.  But if there isn't, and they have multiple directions that they can attack from, then I will almost always lose.  I usually play as Vasari and TEC, but lately I've been trying to get the hang of Vasari in 1v1 Cruel AI, as they seem to have a much harder time than TEC in the same scenario.  Just this previous game I played against the Cruel Vasari AI, after we were both finished colonizing all available planets, we both had control of half of the map, a roughly equal share.  I religiously use the Evacuator as Vasari, and whenever I colonize a planet that is on the boarder of my enemy, I immediately build 3 turrets, and later sometimes up to 8 all within the same area.  Those turrets protect and carry me for a few minutes quite well, but only until they gain access to their super weapon just 30-40 minutes into the game, and start targeting my fortified planets.  In response to being notified of their super weapons completion, I started to build star bases on both fronts since they wouldn't be affected by it.  However, I had to dedicate nearly all my resources to upgrading them for the next 15 minutes or so, but even with their weapons and armor upgraded to tier 2, and the forcefield upgrade, one of them still went down.  If I had a little more time to finish upgrading them, they might have survived, but I'm not sure.  I didn't focus much on building a fleet because both of the planets on the boarder were on the opposite sides of the map from each other (3 phase lanes), so it would have taken a lot of time to reinforce them.  Also, it would have been impossible for me to ever match their fleet strength anyway at the rate they were building up theirs.

Anyway, that is a fairly standard approach for me when playing against the cruel AI when we both have multiple chokes.  If the AI doesn't build a super weapon as fast, I usually continue building more turrets, a few regeneration bays behind them, hangars way in the back, then star bases and mine fields up front with the turrets.  And if my two choke points are closer together, by like one phase lane, I just concentrate on building a fleet and have them ready to jump to the neighboring planet if they are being attacked.  Anyway, could anyone tell me what I could do differently?  In what order should I build my defenses in, and how should I build them?  Also, are there any must-have researches for Vasari on the defensive?  I realize Vasari is more of an offensive faction, especially because of their auto-salvage wreckage tech, but against the Cruel AI it seems just way too risky to go all out offensive early game against the Cruel AI.