Again, I stumbled across some just last night because I took a takedown mission at an industrial anarchy base in one of the systems that I'd previously prepped for farming, and there they were in the security datapoint.
You want to farm SDPs?
Find a system with a high security +++ settlement (the devs have explicitly stated that it's the difficulty level of the setlement that affects the spawn rate, not anything like government type or state) that happens to have a security data port, preferably one that's easy to access if you don't have to care about killing anyone that gets in your way.
Boost the anarchists until they get into a war with the owner, then fight for the anarchists at that settlement.
The settlement will become anarchy, then you can farm it to your heart's content.
If it's the industrial settlement with a single large pad, even better since you can get weapon and suit schematics out of the ops room, manufacturing instructions out of the lab and production rooms, and ionised/compression-liquefied gases out of the industrial lockers and power plant.
Personally, I raid that base layout for all those goodies, the SDPs are just a nice bonus.