The main trick is this:
Click here to view the secret text
×Plates only pop up at the end of a turn.
This means if you step on a plate on the half-turn when monsters aren't moving, then step off, the door won't close until the roach has already moved.
There's a lot of improvisation, as you have to account for goblins stepping on plates as well as endangering you, but taking advantage of this is key. You can often protect the same plate for several turns in a row before the goblins force you to move.
I'm not sure I can get any more detailed than that without providing a demo, so let me know if you need one.