Here's a tip on how to do the smuggling tunnel task by yourself

As soon as you spawn go around the corner and hide for 10 minutes till all of the Exfils open. You can hide over by the cages or by the boat dock. Ect. Then wait for everyone to kill each other and remove at least 50% of the NPCs. Wait until the Exfils open you should have about 7 to 10 minutes left. Until you don't hear running or shooting. Run through as fast as you can avoiding any remaining scavs and hit all of the places for the task and collect any backpacks or easily grabable ammo and get to an exfil. It's an absolutely cowardly way to play but if you're by yourself and you just want to get that task done That's how you do it.