When I say mount it, I mean the angles. Polycarbonate, in my experience, doesn't stand up well when the leading edge is exposed. Spinners tend to cause it to shatter. You are correct that when drilling holes, the area around it does become less resistant. I tend to use large roofing bolts to cover the holes to offer more resistance. Comes down to planning really as to where the holes go and what reinforcement is needed.