I had considered something similar and spent a fair bit of time on the creeper looking at the possibilities. However, I wasn't going between the panels, just along the frame. One obstacle is that the cab and box flex quite a bit. The other problem is that the hose would have to be on a steady incline all the way from the tank to the filler cap or it will take for ever to fill up. Another possibility is to come straight up and use the rear stake pocket somehow. You could just put in a square fuel door like the suburbans had. I had thought about behind the license plate but that won't work either, too low. It can be a real problem for sure.
