Frontal area numbers are a legal CYA device for mfrs. In practice, you would be fine with around 60 sq ft at 60 mph. The wind resistance builds exponentially as speed increases, so keeping speed down makes it possible to exceed their guidelines. Heck, someone once posted about the F150 having a ridiculously low frontal area "limit".
I towed for 140,000 miles with a v6. Mostly 52 to 56 sq ft frontal trailers. But I didn't go 70 like some drivers.
BTW the Scamp frontal area is only about 45 sq ft IIRC; it is rounded, low, and only 6.5' wide.
