I installed the vent kit from @buyouownbeer this weekend. With his directions and a youtube video from Dirt'N'Diesel, it was easy. I don't plan on going through deep water, but like someone said, it's cheap insurance. Besides water intrusion, another reason that I wanted to extend the gas vent line is that my wife complained of gas fumes. Especially after we installed the roof and windshield.
As far a where I terminated the lines, the fan and front dif I coiled up under the dash. I'm not sure where those will go as I'm worried about the wind shield clamps and possible future light bars. The other four I ran up the middle ROPs bar and into the roof ROPs.