Very nice idea, indeed!
I may try this out in PDFRead, as an alternative for smaller screen devices like the EBW1150. Hopefully I can just 'call' your executable from within PDFRead and avoid having to recode your efforts in python.
I remember that the original developer of PDFRead was going to allow some type of reflow of pdf documents, but never released his efforts.
One question though:
Is the split at half the page width "fixed" or can it be changed to a user inputted amount, like one-third or 25%?