Tip: Always call the consigliere to stash your money before attempting to conquer any hostile zones.
There are three sentries in this zone. If you use the gate from the docks, you’ll have easy access to one of the offices where the stationary sentry is hanging out and with a weapon locker with a tac-vest inside. Take him out and any guards nearby.
The second sentry is guarding the trailer itself. You can take him out then plant the explosives on the trailer. There’s also a sniping point in the rooftop of the warehouse, under the Rigolet’s Canning Company signage.
You don’t need to kill every last enemy but if you want to clear the area and collect the cash stashes scattered in the zone, you may do so with guns blazing or stealth. There’s a cash bag near the trash bins containing $500, a cash pile in the second floor office with $1500, and a Vargas painting in the same office.
Head to the marked location and start taking out the guards with stealth kills until you lower their numbers enough so you can easily kill the rest in a firefight without too much resistance. Like before, enter the trailer office and plant the explosives there to destroy it.
There’s a small doorway beside the main gate which you can use to enter the zone covertly. You can work your way in picking off the guards one by one or enter a firefight. Once clear, plant the explosives and leave the area.