You need a userexit or Z program that checks the shipment documents and executes the BAPI for MR22
I'm sorry but you don't. SAP standard does what he wants to do with no development.
The only development I recommend is validating if the freight cost document is created before allowing the posting of the goods issue to prevent user errors.
Though the issue ypu have is Plant to Plant so there is no FI interface open for you to change.
I'm sorry but this is also incorrect. A plant to plant STO can have a condition document where you can add several costs, which then appear in the financial document generated during goods issue.