Check out mutagen (discussion on https://news.ycombinator.com/item?id=30957156 https://news.ycombinator.com/item?id=30957156) -- it basically does bidirectional

Check out mutagen (discussion on https://news.ycombinator.com/item?id=30957156 https://news.ycombinator.com/item?id=30957156) -- it basically does bidirectional, background, transparent rsync. It also does port forwarding if you need that. It looks quite solid for the use case you describe.