Hi again @melihron.
What I had in mind was the equivalent from Duokan for Kindle, or (if you prefer the Android environment) the 'PDF Viewer' (
https://play.google.com/store/apps/d...GZ2aWV3ZXIzIl0.)
What I mean I prefer (b), i.e., to be able to select the margins manually and then have automatic cropping (having selectable zoom/unzoom would be even better, but may be more difficult to achieve),
or just multiple levels of zooming, by pressing a button (something that the current PDF viewers in PocketbookPro 9xx already have, although at fixed levels). Then, one would use the 4-way button at the bottom to pan around the page (this already happens and is the way to read 2-column zoomed documents).
If possible to print everything at bolder (selectable) level even better (as Duokan does), since 'faint' text would appear with more contrast, enhancing reading.
Still, you should receive credit for your efforts, despite of the final outcome.