I am currently flying a round-the-world tour using a B1900D. I have a long over-water leg coming up and there is no way I can make it using the existing fuel capacity. So I would like to simulate the installation of a ferry fuel tank by temporarily increasing the aircraft's fuel capacity to enable me to fly the leg. Does anyone know how I can do this? I have calculated estimated fuel consumption for all my legs so far and would like to avoid using the "unlimited fuel" option if at all possible.