If you go on youtube and search 2015 Versa Hitch there is a video for the installation of the Draw Tite 24887 Hitch. You might want to start there and see if that hitch might fit your SR.
If not, there is a 2015 Versa Note (video) that a different hitch is installed on.
At one time, I was thinking about putting a hitch on my Versa.... so I did some research (and decided against it); I have a 2016 S model.