I'm not sure if I should be requesting this on IC's side, but would it be possible to have containers from Intermodal Containers that are packed with rustable items also inherit that rustability? E.g. Packing a container with a set of iron plates at 50% rustage would result in a packed container at 50% rustage, and upon fully rusting, the container would decay into a packed container of rusty iron plates.
Also, currently you cannot even pack rusted items into containers at all.