Well, with the Zenith power gen, you actually can afford to defend it by sacrificing a bit of the power it is giving you and put some extra caps of turrets on that strategic sweet spot. If you don't need the power at all ( which seems unlikely at higher diff), then you can just take the AIP hit, its not that bad. There are usually plenty of ways to reduce AIP ...and if so, then just try to deepstrike a bit more rather than take more planets.