“New Hampshire NRS 484.619
Nothing can be attached to the windshield that would obstruct the driver’s view except in a 6” square area of the lower corner of the windshield farthest removed from the driver.”
I personally wouldn’t mount in on the windshield. For two reasons. 1 that’s the piece of glass you use to transport youself and family. Why would you obstruct your view and possibly endanger yourself. 2. If you get a good gps it has a nice clear screen that can easily been seen below the dash possibly by the radio. And a lot have voice command. No need to see anyways.