I just have no idea where to even start. Everything I've tried has ended up with a a very large encounter that I just have no chance against.

This remains true.

I felt pretty clever. I used a Minor Illusion to pull a bunch of Goblins off to the edge of a pit and then I Thunderwaved a bunch of them off into spider-town. I was then able to pretty effectively Magic Missile everyone else, including one of those bosses.

It burned a lot of spell slots, but I'd taken care of 25% of the objective!

But I guess I was too noisy and even though I killed everyone in this room, the rest of the camp noticed me and they are pretty upset.

This is not a viable strategy.

I might need more sleep (both in real life and via a fictional long-rest) before I figure this one out.