Yep, there are no points on the non-snorkle side you can attach the grill to....
What u could try is to remove the black plastic (may be difficult, but can be done) from the inside of the body-coloured slats and attach the grill with plastic black ties....Somebody here has done it before, and maybe they can chip in.
Remember to post pics once you do it...goood luck, and dont break anything.

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