complete UV protective glider cover for 15 m ship LS3a

I have Clouddancer covers for the LS8 I acquired recently. They are quite new and look very nice, but I'm unconvinced about their UV protection capabilities. The registration lettering on the fuselage shows through quite clearly which tells me that visible light is penetrating to a fair degree. If UV is doing the same then leaving a glider out for long periods with them fitted would probably result in gel coat degradation.

I've had Jaxida in the past which I think are a little thicker.