Even if you stack a bunch, I guess the optimal way is to find a single station with many factions that hate a single other.
This is a ''rare'' condition, but due to the nature of Elite, there are many.
A station to just land, quickly grabe 5 different stackable missions, and complete them all together.
As numbers will be off, you will probably fly around with 10 accepted missions. Wich is a good run without overlaping too much mission providers.
I do this as an ''exploration'' gameplay, looking for perfect systems im the bubble,
One that the powerplay and BGS never changes what I like about them.
Go out there, do a few courrier missions. They tend to take you to the most random stations.
Eventually you will deliver the mission in a station that all combat missions, does not matter why, hate an specific faction on a cetain system.
Generally Massacre a pirate faction.
These stations are generally in a military system close to a production system like industrial/agricultural/refinary with high population.
Some times System next to systems in infra structure breakdown, will have lots of piracy massacre to that broken system.
I've found some in my time for Both Feds and Empire to farm their reputation. Try looking close to Galatic Power's capitals.
Their BGS state barelly changes.
I don't think there is a precise way to filter this, so I really spend a day jumping around new stations delivering random missions.
Checking their mission board, and when it seems good, I spend some time in that system.
If its really good and never changes, bookmark it and set it as a ''home base'', for your combat ships.
Hope you find your stacks =]
