I would find it helpful to be able to tell my cart to be emptied.
The mechanics so far let me check if i want it to hold a specific item. it could simply be set to if its unchecked it moves it to the closest storage facility or a new button to “Empty”.
I think this is a great idea, perhaps it could be integrated into the wagon shop as an upgrade. That way we could assign workers to haul the cargo from the wagons to storage as they would for the trading post.
The large covered wagon wouldn’t make sense historically… settlers would use a smaller uncovered version to transport good short distances… so… I would go with giving the wagons from the wagon shop more functionality. You wouldn’t have to create new assets for the wagon shop wagons but perhaps manual control and the ability to load and unload like MastaGrogu suggested.