The
NVNTRS.com mentions that the frontal area is 10 sq. ft. That sounds too low to me -- if it is 5' wide then it has to be just 2' tall. My guess it is more like 15-16 sq ft, but I'm making a WAG.
It you took a picture straight on the front with a telephoto lens and a scale like a yardstick beside the fender, I'd be happy to trace it in DataCAD 14 and give you a more accurate estimate.