Losing Sirius REP, best method?

Uma Laszlo, my last engineer.

Im trying to lose Sirius rep, but don't work as fast.

1. Pick mission, delivery, cancel. I get fined 1M in cargo, rep change a little. I need more than 200M for reaching unfriendly.
2. On-Foot combat zone, give profit, but after 3 High CZ, the reputation had minor changes. My specs aren't great for this CZ.
3. Kiling Skimmers in a Sirius settlements (Nolan Stop) after 1 hours, I lost 1/4 friendly rank, 0 notoriety, minimal bounty. But need lot of easy combat with minimal SRV hull damage.
4. Killing NPCs in Odyssey settlements, 1-2 notoriety (I don't know the reason behind this, maybe some no-agressive no-soldier NPC). I don't know the exact reputation lost, the game dont update until some time latter, after my voluntary trip ot the mission.

I have a time limit. The next Alliance-Sirius CG, with LYR giving a special module to overcome the other side.