Permalink for PDF of article

I am attempting to be taught if that is doable, and the way I would go about implementing it. Our web site is a scientific journal, and our printed articles observe this permalink construction:

http://ehponline.org/<article-slug>
i.e. http://ehponline.org/1306796

Each article that we publish has a corresponding PDF that’s out there for viewing/obtain. These PDFs are at present saved exterior of the WP Media construction.

What I’m questioning is that if there’s a method to have a permalink URL for every article resembling this:

http://ehponline.org/<article-slug>/pdf
i.e. http://ehponline.org/1306796/pdf

and that web page both checklist the out there attachment or being redirected to the file itself.

The objectives of doing this might be to:

1. Create an anticipated URL for the article PDF for our readers
2. Make a neater means by which we will monitor PDF views by means of Google Analytics

Any concepts of how this is likely to be performed can be vastly appreciated.