Why would water be an issue unless you regularly roll the car or drive through deep water?
My gearbox is bone dry and clean, the heat shielding on the inside of my gearbox cover, it is bone dry. The heat in the area probably rapidly dries out any splashes. As the floor boards are lower and not sealed from water as far as it is attached to the chassis any water would come through there anyway.
I think it's a bit of a none problem in all reality.
