Well the only place on the wing i can think of installing tank is between fuse and IB nacelles and that is in front of CG point. I saw what happened to Mike's Hawkeye on his maiden flight and i don't want to repeat that with my model.

Here are the pictures from last year with wings separate from the fuselage sitting on the table. This tank could only be installed between LE and front and center spar between nacelles and fuselage.