71 C10 rear gas tank conversion.

[Blue Rat]

Who has moved the gas tanks to the rear in front of the rear bumper. I want to get mine out from behind me. I have no problem with a fuel cell or a tank just needs to be at least 15 gallons for street duty from time to time. But, want it to fit between the frame rails. Also what about the fuel tank filler location. I would like to have one where you could fold the rear license plate down an put fuel in the tank. I am just looking for pictures an options.