Auxillary rear fuel tank for E350

[leighd]

I was looking at these Amazon fuel tanks and prices were surprisingly cheap and looks like it would be a good size in the spare tire underbody area on my EB E350.

Amazon product ASIN B08R9FK2NP
Anyone see any pitfalls of trying to install something like this? Rigging up a fill point and a transfer pump into the main tank?

 

[CaptainBuilt]

Not sure about a filler neck, but a fuel pump, relay and a switch is all you need to fill up the primary tank from that one.