In the article, there's mention of relieving air pressure in the fender wells. Some models have "brake cooling" tendencies with flow into the well, but I wonder if letting air flow out the rear of the area would provide a better overall flow of the vehicle?
Salt/Sand and grime may be harsh on the body or frame, but I'm thinking about how a notch or hole in the often-plastic shield behind the tire would help with improving air-flow. Maybe something that runs the air out and perhaps down under the car. That is, unless you have the area covered
Maybe the front wheel wells could benefit most...
RH77
EDIT: Excellent article, BTW (as I read it again)...