Centre, mounted to the screen.
Printable View
On most cars yes, but Defenders are special as we know... ;)
Where ever you put it make sure it doesn't fall foul of the rules about obstructing drivers vision of the road / side.
My devices are not all that tall, so even on the lower windscreen they only cover the bonnet when looking forwards, so AFAIK that's good enough!
oldyella 76 has got the Vic requirements listed above, and it would surprise me if any other state was materially different.