I've gone ahead and put some vents in the back of the bonnet to help with under bonnet temperatures. Whilst driving, the temperature hovers around 95°C but starts to climb in stop-start traffic. The radiator fan does cut in and bring the temps down fine but I figured some extra air flow wouldn't hurt
I decided I wanted the mesh to be flush with the top of the bonnet so I made a press from some polycarbonate offcuts to form the mesh.
With this made, a dremel was used to make the hole then some sikaflex to hold the mesh in place.
Job done!