I agree, unless it is water tight. My design is based on louvers that I have seen used on boats, so I'm confident it would work. On the other hand, I'm not going to fix that which isn't broken. I've been keeping a close eye on my thermostat and it hasn't ventured above normal yet. Not even in 107F heat of the way back from Bishop with the AC running. I'm not cutting a hole in my hood until I have a need for more cooling.
Well with our 100+ temps, driving around town and cruising at 75 on the hwy is making the needle climb in my H3 with the a/c on. It gets to where I feel the a/c "warm up" but the DIC never gives me any info or cuts the a/c off. So I'm pretty sure it's running hot and a hole in the hood should help. I ordered some louvered panels and will make the cuts for them soon, it's just too hot outside when I'm able to work on it (night shifts can suck). I'm going to put two 10x14" louvered panels just outboard of the fake louver and make some trays or shields under them to channel water away.