is a GoPro really going to be blocking that much that can't be cleared with the usual head movements required to see around the aircraft frame?
Perhaps not, relative to other obstructions such as the wing etc. but the thought of obscuring part of the purpose-built windshield in a PA38 is surely a hazard to flight safety...and I've had an airprox with an F16 - blind spot created by the arm of my sunglasses. As you're going to PCL this weekend, why not speak to the large schools exhibiting and ask their opinion on this.