There is a limited selection in regards to darker shades and privacy options with flyscreens as they are not really designed for that purpose. From what's available I believe the Cyclone 1220mm Miniweave Insect Screen - Linear Metre would be the best option. It has more strands per square centimetre and is a tighter weave than traditional flyscreens. As the Miniweave has more strands it would be the best for obscuring the view.
Another option might be to reduce the size of your spline slightly allowing you to install two layers of fibreglass flyscreen. If the holes are offset between the layers then that would certainly provide a visual barrier.