Here's something to help you get started sort of:
Click here to view the secret text
×Remember that you can drop two of those four trapdoors, which should make it much easier to avoid roaches, in addition, certain tricks for killing roaches from both sides in a quick manner will help. Namely
Click here to view the secret text
×use a horizontal sword and lure roaches out from the corners one at a time (stepping back so you get one by one) and you can clear spawns very quickly.
This might get you closer; I can give more hints as needed.
____________________________
If you need to think outside of the box, then you didn't build a good enough box.