Southern Union Camp
This is located high up in the woodland area north of the district. There are only four hostiles in this gathering. You can take out the two enemies talking near a supply stash by shooting at the explosive canisters beside them. You can go loud since you can take out the remaining enemies or all four of them at this point.
Southern Union Residence
This small backyard gathering has at least two cops in the fray. Circle around the garage and lob a grenade aimed to the cops to take them out instantly. Deal with the survivors afterward. Once done, collect the stacks of cash in the party area then destroy the supplies inside the garage as well to deal more damage.
Southern Union Heritage Center
This is a guarded compound. First, using your silenced weapon, take out the two guards outside. There's a lone roving guard that will stumble upon the corpses so you can just ambush him or take him out as well. For the remaining enemies inside, you can proceed with eliminating them loudly - just prioritize taking down the sentry first. Destroy the remaining stashes by shooting the explosive canisters then loot the cash in the area.