Thank you! Hopefully this still works! I've had soooo many crates but pretty much gave up on trying to solo this, figuring it was way more trouble than it's worth, and/or wouldn't be able to be done. I haven't even completed it yet, so hopefully this will help a lot!
If you are doing solo, i recommend doing it in a public server as cop, only because NPCs are alot stronger in private servers. And if you are a cop you can get there quicker!