locked in (EDIT: locked inside) is indeed insane. I think it's impossible, since you can hardly secure more than 3 energy/sec after the terrain is decayed (after a few minutes). And the drones are so insane, I think you can't destroy them with blasters. That means you need a dark beam in 4 minutes, with an energy income of 3 minutes. The best case I can image then is a infinite stalemate, where you switch your dark beam on just enough to destroy all the drones.
My most promising try is shown in the screenshot. I mimicked deathsandwich's approach. I managed to bring the health of the emitter back to 0.67. But even if you destroy that emitter, it won't make that much of a difference, since after 4-5 minutes, most creeper will come from the emitter(s) below.
EDIT:
@deathsandwich: I think the unit cost upgrade is better than the reactor efficiency upgrade on this map.