I became aware of this problem some years ago, as did BMR, so you probably have the new/improved design. Look closely at the gusseting details to be sure (07 Boss's pictures don't show them clearly enough for these old eyes).
BMR did revise the design, as discussed and pictured in the first post in the following link.
A look at BMR's Current S197 Tubular A-Arm Offering | SVTPerformance.com
As a now-retired structural engineer, I feel that the elimination of stress concentrations was a minimum requirement for unrestricted street duty.
You might be able to cut strip-only driving a little slack due to the brief nature of the "drives" and the resulting smaller number of fatigue cycles . . . unless you're getting air under the front tires and letting the car just slam back down. Though at that point it's on the car owner/driver/crew chief to do far more detailed inspections of suspension components than any ordinary consumer ever would, and probably more than any Ford tech would ever think to do during a normal scheduled maintenance.
Norm