Accounting Overhead for inventory items - without manufacturing

We have a monthly rental cost for storing inventory items that we want to allocate to all inventory items.
The monthly cost is a fixed amount. But it should be prorated to all items.
This cost should not be just accounting, because it should increase the average cost of each item monthly.

The Cost Method we use is the “Perpetual Average”.

We tried to use the Cost Scenario, but it didn't work, because it requires the Work Definition setup. But we don't have production. We only buy items.

We tried to use Accounting Overhead Rules, but it is based on transactions. And in our case, there is no transaction: it is about the balance of each item at the time of allocation.