here are those wall plates I was talking about
:
http://www.av-outlet.com/en-us/dept_257.html
They are the only place I have seen that product.
and I agree: always go with in-wall rated unless a building inspector or master electrician tells you it's okay to do otherwise. Else you may have a nasty legal fight if the wrong wiring acts like a fuse and carries a fire throughout the house (which is the sole reason for special CL/plenum ratings on wire).