According to AEV the offset of the spare tire is to make it easier to reach the door handle, especially with larger tires.
The tanks are approximately 2.3 gallons each, and AEV does not recommend them for potable water. But hooked to a pump would be a great source of water for clearing mud out of radiators or wheels, washing hands, etc. It's also weight below the CG, which is a cool idea.
In the YouTube videos where AEV shows this bumper, he actually pushed the Hi-Lift jack sideways with a good shove to show how the tabs hold the jack in place. Not as good as a notch, but still pretty decent.
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I seriously considered this bumper/carrier setup, specifically for the fuel carrier, and non-potable water tanks. Pretty sure I'll end up with the LoD, since it has a rack above the spare tire. That really works out well for my application.
So many great American made bumpers out there. Good luck with your decision. :beer: