The manual says 8 degrees is optimal, though 0 to 16 degrees is allowable (page 6). I'd hope that I'll still get most of the protection, it's pretty near to 16 degrees (the picture is a little deceptive as to the exact angle).

As you say, I don't have a lot of choice here. Also, with the swoop in the top left, the angle makes the top left of the display visible this low down.