Has any one installed actual heat extraction vents in their hood?

 

Yes, that has been done, not sure if it helps but probably does. I would think water ingress could be your next problem with a louvered hood. I don't think the engines radiant heat and engine compartment heat influence the operating temperature if your cooling system is working right. At least in my experience it does not. If these were air-cooled VW's then yes. My only concern is the wear on underhood accessories and components. Even with that I don't think it is as bad as it appears. Humans have crappy heat tolerance. 150-200 deg to us feels crazy hot but is not hot in the world of properly engineered plastic, metal, and machinery.
I have wondered if the lower engine tray cover has influence on airflow. Mine is removed at the moment but maybe tt funnels the air better out vs just causing a low pressure effect off the fan. Sort of an extension of the fan shroud.

 

The seals are for LR's convoluted cabin air filter system. The idea was pull outside air from the base of the windshield through the filter and in to the cabin air intake. The rear most seal is so air does not bypass the filter, the front seal is so the cabin air does not pull in engine air heat. I pull them both and keep my AC on recirc. The recirc setting pulls air only from the interior, and pulling both seals allows the hot underhood air to escape at low speeds, at high speeds the high pressure zone at the base of the windshield pushes cool air down in to the engine compartment. In both situations the engine compartment is cooler.

 

Right on about using recirc. This avoids any issue with drawing in the extra heat. I only use recirc anyway, it’s better performance from the AC regardless IMO.