Hybrids? Ouch.
Honest fact is, my experience here is probably on the naive side. My AIP was fairly low due to my recent focus on Gravity Drill/Special Ops Commander combined with hybrid hives and two nearby raid engines.
Near that first CPA, these logistics commands were defenitely going down w/o support. I supported most of them with nine spiders/nine snipers/1 FF Mk1/4 Missile Turrets/4 MLRS turrets/4 Laser Turrets/4 Basic Turrets. I also supported them to this point with a full cap of MK1 Riot Starships.
Most importantly, I supported them by using the 'reserve power' control so I could afford to have one or even two go down.
I could have done better setting up my defenses, to be sure, but it wasn't about stopping an entire enemy force, merely about setting it up for defeat in detail as cheaply as possible, and kiting with Frigates and similar. If I can make it past the thirty or so hybrids readying to attack outside my homeworld (with 20 more on the way), I'll be able to do a superior job of testing this distributed defense.
Up till around planetary system six or so (no Data Centers, Civ leaders on) and the CPA at 4:30... they held off things decently, excepting Armor Rotters, and just about anything else that doesn't need to worry about engine damage (lucky not to face any bombards or sentinels). After I popped the sixth world, they started going down even with Bomber Starship, Riot, AND Raid Starship support. it's a flawed defense, but it worked for what I was currently facing. It wouldn't help with the hybrids at all, of course, but thanks to the mistaken unlock of MkIII Raid Starships, I could actually kill the small groups of hybrids very quickly. Right before this CPA and mobilizing hybrids happened, I was starting to re-evaluate my defensive setup, but got interrupted before I could come to a fresh conclusion.
Frankly, I'm less confident about my suggestion than before, but if you're actually putting enough spider turrets in place to stop the later waves, then its not working. I fully expect to have a command station dead with several hundred AI ships at a standstill while I'm busy stamping out a fire elsewhere.I am planning on establishing a new front line with about six systems bordering enemy territory, and two chokes a little further back, with two gravity drills dividing my empire in three. If I still think it's useful with the horrible restriction on mobility and the inability for each front to support each other, then I'm onto something for lowly 7/7. If not, well... I'll explore it again in a more normal, less grav-drilly game.
When the CPA comes around seems to be the very weakest part of my whole defensive theory. The defensive hybrids mobilizing from much deeper in AI territory (past the gravity drills) can ignore things, and I won't have enough otherwise useless (due to range, low mark) bomber starships or (due to gravity drills) Raid Starships to stamp out each fire. When it's only a half dozen on one system, I can usually pull something off committing my fleet ships. Exo-galactic threat will also probably push down my defenses too frequently for this to hold up as well.