Excluding Secure Items from a PDX Export

Hi,

We have various items in our system that are considered secure and not for export outside the company.

We have access to these items controlled really well, in that non cleared staff are unable to see or access these, however, we wish to ensure that cleared staff can not accidentally include these items in a PDX export.

Has anyone done this in their Agile systems? If yes, how?

Or does anyone have any idea's on how to achieve this?

We do not want to have to create "restricted" accounts for the sole purpose of exports, as this adds more maintenance work.