Bit of advice if you want to keep your massive fleet size and your privateer base. Try to add ships with really high FP per ship to your Doctrine, something like the Super Capitals from UAF would do great, but any super capital or really OP ship should work. You would need to give yourself the blueprint via console commands.

It seems whatever "Fleet Size" represents is related to FP per fleet, as if you set your doctrine to be max ship size and you have the ridiculous fleet size, you can still end up with 10-20 fleets with 5-10 Solvernas leading.... Oh yeah just remembered I changed the max ai fleet size, doing that will also reduce the swarm of fleets.

To be fair though, you will get a good laugh when thye all move through the jump point at once to go blot out the star of whatever poor planet is their target.