[elhigh]

In my experience the rear bumper has next to zero crashworthiness - I utterly destroyed one on a curb at about 3mph. A replacement was only $125, and built to the same standard - does that tell you what it's good for?

In my truck, the fuel tank lies ahead of the underbed-mounted spare, which itself is nested in a square of underbed framing members. A crash would have to be pretty darned devastating to get through all of that to damage the tank. Of course, something coming from the side is another story, but there's no bumper there either - moot point.

Pull the bumper. If you never tow anything, you'll never miss it. If you do tow, stick on a frame-mount hitch receiver and go nuts.