Its a bohemoth! That just might impede your view, just abit. You can safely drive without rear view mirror on your windscreen, think trucks and vans. It takes some getting use to, provided your side mirrors are good you'll have no problems.
Come to think of it, you will be forced to drive much more carefully aiming for total awareness around you, all the time.
Do they have Tea Chests in the US? Old methods of storage, rather large timber boxes made from thin hardwood ply or masonite. With steel edges and corners, riddled with panel pins. They are very 'rustic' looking, raw timber with old company logo's stamped the size of a dinner plate on the side. They kind of resemble treasure chests.
You could dress down your cab to look like that, to deter would be thieves possibly? retrofitting the grills only of the cheapest and nastiest 6 x 9's to the top of the box is another method, after spraying it matt black, crack heads generally know their prospective merchandise and wouldn't bother stealing really crappy speakers.
On the flipside you could toy with your mates that its the two 6 X 9's that are making all the sound from your box
I almost couldn't sleep when I was at your stage of completing my build

I bet you're feeling great now!
Well done again mate