Agree with a few above, ours blew off the top at 60 mph. Watched it happen myself as it flew across the other lane. Held down by 2 screws about 2" long and a bunch of dicor sealant.
re the thin luan....
you could always add a larger footprint board/metal plate to mount to....
--> https://www.google.com/search?q=wing...of+mount+plate
it would disperse the load and (sounds like) would be better than stock
but then you'd have to worry about falling through the roof to do it !!! teehee