Well, since every faction is now at war with each other basicly or hostile to some, why not increase the hostility of NPC's a bit. It may not solve that 100% full issues due to no spawning, but still, it may cool down the server when there are 180 people, half idling.
For example, unless the server is uber full, you cannot idle more than 20-25 seconds at one place in Omicron Minor, it is very probable that 5-10 NPC ships will blow you to space dust in 10 seconds. There are some systems where you can feel uber safe, we can remove that feeling.
For example, before 4.85, in Unknown (now 92) system, you never got any Nomad spawns, so it was possible to sit still there and go jogging (I never did though lol), now if you stand still and write 3-4 lines of messages, some Assassins will show up to blow you off. And you cannot escape that easily since they have CD stuff on board as well.