14 gage metal is very, very thick if people won't be climbing on it, crashing into it.
Let me think about it a bit. Do you want the interior of the engine compartment to be completely "hidden" from external view, or can the louvers be short enough and spaced widely apart enough to "see through" but not "poke fingers through"? Commercial engine operated commercially, or will this be operated by the (very ignorant, very stupid, and very dangerous) public?