After a good bit of research...done.
To the left inside the large storage bay, added a 90deg cut off that tapped into the city water supply. It's nuts that Winnie doesn't have this on the stock coach. 30 to 40 bucks in valves and some pex pipe.
Also plumbed in another water tank with this upgrade. Added another 30 gal.
Painted and screwed down 2x4s secure the tank from sliding and it is wedged against the bottom of the bed so it can't go anywhere. We've road tested camping a couple of times and this gives us 4 showers now.