Usually there is a way around.
Finally I decided to add a public task to the component (by the way, it is a PDF Indexer) so now there is a bridge to JCron to interact with it. Basically what I do is trigger periodically the PDF indexer, so the text inside PDFs is inserted in Joomla's DB.
I assume that the risks are minimal, since users doesn't know that there's a path, and if they found it, well...they only can help JCron indexing more frequently.
All is working like a charm, thanks again Ovidiu for the orientation and inspiration!