Do you have some kind of splash guard or seal between the filler neck and the window cover panel? If not, you might want to consider at least a foam or rubber gasket. Any Fuel spilling out of a fill can or coming back out of the fill neck from an over-fill is going to spill right down inside the truck.
Not sure if there's anything you can do about it, or if it's even an issue, but the closed off window panel makes it hard for the fuel man to see when the gas starts filling up in the filler neck. He won't know when the tank's full.
Man your right I need to seal this up. I was trying to keep the door operational. Thanks for the heads up.
General safety rules for MORE, SNORE, BITD, SCORE say that it must be designed from fuel entering the passenger compartment. That is why most teams stick the filler through the rear stationary window and seal around it.