Here are some instructions for setting up Syncthing on a Kindle Touch:
Setup Syncthing on Kindle Touch.
I exclusively use KOReader/KSM on my Kobo Glo, and am a heavy user of KOReader on my Nexus 7. I use Syncthing to sync my books and pdfs (among other things) between the Nexus 7 and a laptop and a desktop. I would find it very useful to sync the Kobo in this way as well.
I am busy with other projects at the moment but this idea seems worth looking into to me.