We decided to not use a stack mod as it always brings a lot of risks to the cluster and increases loading times. We instead changed the stack sizes with Vanilla config options and adjusted the weight with a plugin. The weight reduction will not be shown ingame because the plugin uses inventory weight reduction to adjust weights! The weight shown on the item is not the weight that is applied to the inventory.

This is a list of all items, their stack size and the weight applied to your inventory per stack. Any additional weight reduction that is provided by a dino is of course applied on top of these values.