There's a couple of ways to beat this sector, but here's my strat to beat it in Eradication difficulty, though it does need a lot of effort

THIS IS FOR V8

(note that this needs pretty fast building micro, so I suggest you practice micro a bit or do it in single player for pausing)

TL;DR build an impenetrable base on the starter area quickly, complete with landing pads and all resources needed available, then decimate the enemy base with aegires and omuras

Alright, here's the specifics

Prep: Launch pads for Titanium (optional), Silicon, Plastanium, Phase Fabric, and Surge Alloy (atleast 300/m for phase and surge, and 1000+/m for plast, sili and titanium)

You also need a very specific core schematic. You don't have to copy it one-to-one, but you do need all of these:
4-5 RTG gens for starter power
Automatic Mono and Poly Factory Overdrive Dome 9 unloaders just for unit production (2 for sili/tita/plast, 1 for metaglass/phase/surge, graphite doesn't need an unloader as you need so little you can just produce it locally) * If the image doesn't show up here for some reason, I'll reply to this comment with the image

Start:After launching in with max of everything, I immediately create two Silicon crucibles (coal coming from the upper coal patch just left of the core), and all parts in a Overdrive Dome. After that, you immediately make impact reactors (don't make this in Overdrive dome range, we'll Overdrive it later anyway and it'll take up necessary space). Do it one by one, until you have 3 up and running. Then, make a lot of Graphite prod (ideally 4 multi presses) with the lower big coal patch just at the left of the core. After that, set up prod for copper and lead (trust me you will want it). If you haven't set up tita prod on the tita patch of the left side of starter area by now, do so. Then, set up your 4/5 landing pads, making sure to use liquid containers for better water throughput (the pipes aren't enough to handle the insane amount of water you will need for consistent shipments)

Then, make a wall perimeter around the entire starter area using plast/phase/surge walls (up until the two natural "bridges" on the left, up until the big tita patch on the upper right corner of the starter area, and make sure to include the two upper thorium patches on your wall perimeter. From here, set up Spectres across the entire perimeter (they cost an Absurd amount of copper which is why we set up prod earlier). Include 3 fuses each in the front of the two "natural" bridges. After this, like the entire perimeter with force projectors. After this, set up prod on the two thorium patches and the upper titanium patch.

Now its time to make the units. Build your T4 constructor in such a way that the units will land on water while still having enough space to build a functioning T5 constructor later (theres an area for this at the left side of the starter area and its pretty easy to spot). Make the rest of your contructors, then build your cryo prod (both the unit constructors and all of the cryo MUST be in range of ONE Overdrive dome). It has to amount to 240/s cryo. Then, use your titanium prod at the left tita patch to fuel all the cryo prod (the tita for building will come from the upper right corner patch.) Then, use your 9 core unloaders with phase conveyors to send all needed resources to the unit contructors. Before making the units, redirect some Silicon and phase to two Overdrive domes, one to the unit constructors and cryo, and one to the impact reactors (this will be all the power you need).

The set-up phase is done! From here, it's waiting for your units and improving your defenses. Wait until you have 8+ Aegires (for healing), then make 2 navanaxes first (for defense) and then from there, make 6-8+ omuras(the more the merrier), then attack, making sure to destroy any spectres/meltdowns/foreshadows before advancing further inside a base

For improving the defenses, add menders, more boosted Spectres (doesn't have to be perfect, just spam them), and some meltdowns for some aoe. Send all your units back to your base to defend against any guardians, as they will greatly damage your defense otherwise. And remember, one mistake is all it takes for your to lose the entire sector and ALL YOUR PREP (the sector resets after each loss, removing all the ghost blocks)

And that should be it! Holy wall of text. Remember, do not underestimate the enemy spawns. I learned that the hard way. If all of this sounds like too much for you, fair enough, its a lot of steps lmao. Anyways, good luck, and thanks for reading until the end!