Handling units with barcode

We currently use handling units to identify pallets and boxes in our warehouse. These units contain an arbitrary amount of products. We have considered using batches for this but batches allow only one product per batch.

Is there a way to achieve this in ERPNext? In the end we would like to have a list of handling units that when opened display what’s inside of them.

My first try was to add a DocType “Handling Unit” and a field “handling unit” to the DocType “Batch” - This way every batch can be part of a handling unit.
What I haven’t been able to do is to display a list of the batches’ contents from the handling unit screen.

Any thoughts? Maybe other ways to do what we want to do here?
Help would be appreciated!