Dead space in water tank

The flaw being the manufacturer isn't concerned with doing it any better. Many are the same, my brothers bows so far it rests on one of the axles.

It is a flaw. I had the same thing on the hybrid I used to have. I added a support in the middle and also another going across the bottom of the tank from support to support. I couldn't get all of the water but it got me a few more gallons. My biggest problem was getting all the antifreeze out of the tank. My quick fix for that was to use a 1 x 4 board. I could squeeze one end of it up between the support and tank on the end away from the pump pick-up or the drain. Then slide the board under the tank until the other end went under the other support. This lifted the belly of the tank so more water/antifreeze would come out. Do not drive with the board in there unless you find a way to secure it. This is what I did until I got another support made and installed.

But you will always have a few gallons available in the event of an apocalypse

Flaw.

The tank is not adequately supported in the middle to keep it from bowing down.

Flaw...