Long response but to answer as completely as possible, this is the only way.
90 percent of the airflow isn’t blocked by the lights because of the space around and behind them. To block off 90% you would have to literally stick a sheet in front of the a/c condenser then cut out 10% off of that sheet. Not trying to be a smart a$$ just sayin’.
The grill still has 100% access to open air. The fan clutch’s condition/efficiency dictates airflow. above a certain speed, the radiator’s fins and the fan itself will block more air than some lights spaced 6” from the grill. It’s all about the fan. And then there’s the a/c condenser also blocking some air. The only way that air gets through the radiator is by the fan pulling it through.
As for the grills, they help in slow speed “hot” operation. I reasoned that the fan system pulls hot air after heat exchange, it needs an exhaust to realease that hot air. I placed them in the middle of the hood since this is where hot air will likely collect when the engine is off to help with heat soak. After 30 minutes with the engine off, I am seeing 10 degrees cooler than without the vents.
I use a Koso gauge with sending unit installed on the upper rad hose. Before the vents, in 95 deg to 100 deg ambient temps, I would run 190 deg at a dead stop off road. Now, it runs 185 deg.
I can’t say the temp drop is from cooler coolant or engine temp. Might be from hot air moving away from sending unit itself.
I wish I had the forming tools to make these but Rod Louvers made them for me.