I was averaging 600 mil for 120 pirates, which takes about 3 hours. On top of that, with level 2 powerplay and a KWS, I get around 130 mil in bounty money per run, so 730 mil per run -10% for NPC fighter crew. We tried doing it in a wing of 2, but you don't get more money. Avoid the wing missions for the best payouts because the payout per pirate is much lower. Non-wing missions pay 1.33 mil per pirate, while as wing missions only pay 0,5 mil per pirate. Obviously, you need to be alied with all factions to get the best payouts, and you need the maximum number of factions offering the missions for the same pirates. In my case, that's 7 factions.