man if your going through water that deep, if you slow down enough to not wake or you stop- You will hydrolock that engine. I would not be running any other aftermarket airboxes or intakes if you plan on doing this again. Also you have vent tubes going to various components axles, transfercase, etc...that could be full of water now. I'd definately take the time to service those points. New fluids are cheaper than new components. Only mentioning this because some people have no clue.
You need to be looking at how you are going to build a custom snokle to save your motor before you try to figure out how to keep water off your windshield.
1st thing that comes to my mind how to divert water would be a V setup on the hood. Two L channels 4-6" high. Make it out of some thick clear acrylic so it would be translucent. It wont be pretty, but function over form... it would push the water off to the sides.
If you have a video deck, you could put a cam on the roof...blind drive through that if you ever get back in that situation.