Those are good practice pointers, and I agree with everything you're saying in principle. At the same time, it was not uncommon, in the bad-old-days before we had electronic filing, to make a copy of the signed return before sending it to the IRS and to retain that copy in the client's file. I'm essentially looking for the modern equivalent of that practice with an e-filed return.
You may assume that I am authorized by my client to do what I am doing and that I have considered the business and other implications of doing so.
My question is purely practical: Is there a way to have the PTO software generate a PDF that shows the return, signed using a PIN (as the Form 8879 indicates it would be), in the form in which it was sent to the IRS?