You can get around the E-Signature request by scanning in the 8879 (and any others) and unchecking the 8879 checkbox in the E-Sig pop-up box - then select "other document"  browse and attach the scanned in ones. The document/s will open and you have to manually add the signature and date prompts before sending. This way you can still attach billing etc.

The problem still exists when trying to E-File however.