This is a really fun challenge, which is great because the other two this week were kinda lame.
I thought a lot about this between episodes, and all my thinking came to nothing in the end because we found a much simpler way to get this complete. But in this episode you can see me experiment, refine, and go through my process. If you like that sort of thing.
But I still think you could game the game by finding an area dense in enemies, setting your difficult to the easiest level and laying loads of C4. Get them where you need them, then swap to extreme and detonate. Up to you.