Illustrator :: How To Automatically Add Certain Mark At Certain Place In The File

My job is making PDFs "ready for print" - checking colours, making sure overprint is on where needed, adding trapping where needed, etc. After I'm done doing this, I add a logo outside of the printable area as proof that I have checked the file and it's OK for print and the date. This is always on the same spot: 5mm left from the left edge of the design and 5mm below the lower edge.
 
Right now, I have to keep the Illustrator file with the logo/date open at all times, go there, copy the image, go back to the design I was working on, paste it and enter the values manually to be sure it's in the right place (and then edit the date, of course).
 
It's time consuming and I was wondering if there's a way to make Illustrator place the logo and date on a pre-determined location without having to keep the file open. I can't just make an action that "places" the file there because then, I can't edit the date anymore.