Need Alternate option for Audit trail on Invoices

Hi All

Business need a mechanism to get below details, after creation of Original AP invoice

1. Any updates on Payment term and payment methods (with user namd and time stamp)

2. Time taken between invoice creation and validation

3 Time lapsed between invoice validation and invoice accounting  etc

Now as per our understanding we can achieve this functionality by using Audit Trail. But Audit Trail is not advisible on transaction table as it will lots of overheads on storage.

So, need to know is there any other way of achieving the same ?

Regards,

Rahul