To answer your question, the fuel tank is located BEHIND the actual barrier. It is covered on the cargo side by a titanium (YES Titanium) plate. If you are going to screw into the side facing the seats, you should be okay. If you are going to screw into the cargo area side, the only steel to screw into is near the top, where it's vertical. The angled portion is the cover plate for the tank.

Hope that helps.