Considering that you have a total of five things that can press plates, putting the roach there won't help all that much and I don't think it's possible anyway. But,
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×you do need the roach to be there at one point. This room uses a trick that's kind of common in this hold in that
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×you can gain as much distance as you want in either the horizontal or vertical direction and you need to force the roach to not move diagonally to gain distance in the other direction to hit the plates.
I can give more specific hints if necessary.
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If you need to think outside of the box, then you didn't build a good enough box.