Hi Sean,
Send to PDF was built with Adobe functionality directly tied in. You cannot use any other PDF Writers to use the Send to PDF functionality. This is not likely to change, as the Send To functionality is generally seen as "old" functionality.
If you are already printing to screen, you can print to the PDF printer, then attach to a manually created email.
If you want to use different, automatic PDF functionality, then you would need to use the Email options on almost any report, then click the email button rather than printing the report to screen. This is what we consider the "new" functionality, and doesn't require a PDF printer at all. Instead it uses Word's built-in PDF functionality.
As Beat mentioned, Templates are required for this process. You will also want to be on GP 18.2+, or the most recent GP 2016 Year-end update, as new Office rules required us to rework our Template functionality.
Thanks!