Wonderful Renders you are doing. They are Superb! Some of these should be in the "Renders and Illustrations", nice and big, for "Desktop Backgrounds". As far as drop tanks, and gas tank filling points, the main concern is to not have a tube. You want the fillers points right on the tank. A tube leading to a tank could leak and cause major leak, and vapor problems, leading to an explosion, or crew poisoning. Every aircraft I ever filled had the fuel tanks like this.