Containers being held by a PC or donkey should affect the total slots used. For example, when a PC holds a Cart it takes up two slots in their inventory until they drop it.
There should be a associated with a container that indicates it is being "held" by a person, donkey, horse etc. They are all bulky and take two slots, so it shouldn't be that difficult to indicate. Think of it like a button that increases a character (or hireling!)'s total slots held by 2.
Containers being held by a PC or donkey should affect the total slots used. For example, when a PC holds a Cart it takes up two slots in their inventory until they drop it.
There should be a associated with a container that indicates it is being "held" by a person, donkey, horse etc. They are all bulky and take two slots, so it shouldn't be that difficult to indicate. Think of it like a button that increases a character (or hireling!)'s total slots held by 2.