Impossible to add a new cargo?

It seems icargo.create can only create a cargo that is in the session. As soon as you quit and reload the game, the cargo's gone from the inventory. It seems as if the savegame file does not add the new cargo's data in it. Is there a workaround?

Okay... I now know that savegame's inventory is only supposed to save 611 cargo types. I suspect that it's not in any pog file, but in the executable itself. Can anyone confirm this?

Is it still possible to create a NEW FILE within the game? Can you add Windows API into the pog file? Or is it just game's fuctions only?