I thought I would share some pics of my tail light gas filler door I made for my truck. I saw a few on here, but didn't really like how the tail light folded down. I figured it would get in the way while filling up. I tried to go up using hinges and failed a few times. I wound up just drilling the housing and using a 1/4-20 bolt through the housing as a hinge. I had to weld a little tab on the left hand side for the bolt to go into. I also made a little sheet metal catch the holds the light up while I fill up. It is spring loaded closed as well.
Here are the pics
Lynn