Not to beat up on anyone, but polycarbonate is simply not a good fit for this application. I'm sure the manufacturer, and engineers at Van's, were ok with this cold formed wrap at such a large radius, and it was within 'spec' for the material.
The problem is; this imparts stress, and sooner than later, these cracks, risers, and crazing results. On a rear window, this is not critical, but I hardly see how it can be 'stronger' than plexi, when it eventually busts in half!
The F-22 has a huge lexan canopy, but you can be sure that it is surface hardened, tinted, and molded at something well above room temperature!!!
Lexan was first spec'd as a security glazing, and as such, needed to perform vertically, and relatively flat. Laying it down and bending it is starting to depart from its' best characteristics; such as impact resistance.
Yes, in the 1970's, we were lured by the appeal of Makrolon, Lexan etc. and made several windshields flat wrapped, siliconed, and drilled, 6" from a fuel filler cap, before coming to our senses.
I just hate to see others go thru the same trial and error process .......45 years later!!!!!