Model element locations on sheet

Hi all,

I ran into a problem concerning sheets and model elements.
I would like to place elements, like symbols and views, on my sheet on the position, or related to the position, of certain model elements.
In this case, I have some beams and want to place an arrow in the middle of it This arrow should point towards a section view concerning the beam. The situation is sketched below:

What I know is the Cropbox size and position in the model coordinate system.
What I also know is size and position of the Viewport in the local sheet coordinate system.
These things have nothing to do with each other and can not be easily scaled to get the right result.
The problem is: as for as I know, I can’t get the cropbox location information on the sheet.

The result should look something like this:

Does anyone know how I can determine what the beam location on the sheet is?
Or at least the cropbox location on the sheet? I can translate that to a beam location ofcourse.

Thanks all and happy holidays.