Hi, I'm new to the site as well. I've been in aviation for 13 years and have education/experience in aerodynamics. My first thought after seeing your undercarriage pan was that I'm jealous and want one badly for my explorer...
My second thought is that it would probably work a Lot better if it had a very slight ramp/spoiler aimed downward toward the ground. I'm trying to picture the airflow if the vehicle was in a wind tunnel, and how you want it to aim down just enough to make the air clear the rear suspension, but not cause any drag. If it aims down too much it will reflect off the ground and probably try to lift the rear of the vehicle or just swirl around.
Excellent job, I hope to have as much luck with mine as you did.
Have you considered putting clear covers over the recessed fog lights? I had noticed on the new retro Ford Mustangs that even though the headlights were recessed to match the old style, there were clear covers over them that smoothed the front of the car. Your sunken fog lights act like air brakes. Aerodynamics 101...forward facing holes that aren't feeding engines = bad.
Very true, that's why if your temp gauge goes up with your grill block, it's blocking TOO much. Temperature should be regulated via the thermostat. Not just using the fan to limit over heating.. One of my little pet peeves.
spacing or venting your hood towards the rear helps in lowering your engine temperatures allowing the air to come out at the top, I did drifting for a while and experimented quite a bit with it, putting a half inch spacer at the rear of the hood kept the temps 10 to 15 degrees cooler and had less engine bay pressure