I had no idea these existed! This is a definite buy for me. I love your location as well. I may consider a more permanent mount in your same location to prevent theft of the unit though. The fuel door is a cool idea as well.
I have seen people do the gas door thing but only on the sub '10 models. Since we have the capless and it has that rubber piece on the door i dont think it will fit there. But i didnt test it out. No one ever sees it or knows what im doing when i use it. Its funy to watch there facial expressions. You cant see it from your seat either so its not anything your gunna see while you drive. It was the quickest acess and least visible spot i could find. http://accessories.ford.com/keyless-entry-keypad.html