Hmm .. rather stupid idea, and of course totally OT, but:
would it be possible to add an empty margin at the bottom of the pages (pdf-to-margined-pdf) and use this as "notepad" (scrolling down to write, up to read) but while reading just skip it?
It of course wouldn't be as good as a real notepad (e.g. notes would appear only on one page). Alternatively: Is jumping backwards (to the last page) and back to the previous page possible? Then just add a couple of empty pages at the end / front / wherever (e.g. adding a link at each page-bottom, and a "back" button on the empty pages)