Camino Potugese in Reverse

From Tui to Santiago I could barely follow it forward; it was a well marked rabbit warren. All things are possible, though. Good luck!

Have a look at this website there is an entry for walking back from Santiago to Lisbon, Hel walked it in winter as well. In the couple of years since they did it, there has been more signage put up for going to Santiago and the Fatima groups have been better marking the way from the Portuguese border to Fatima which will serve you well to at least Coimbra + there is more options for pilgrim dedicated accommodation. When I walked north I met a few people going south, here and there, one was a young guy who had walked from Belgium and we met him just outside of Fatima http://www.travelblog.org/Bloggers/Me-Too/

BlurryBrian, you’ll find the backward Camiño very well marked, just have to follow the blue marks for the Fatima Caminho. I've done the regular one this year, and I was really really astonished with the very well marked Caminho to Fátima.

After Fátima, it could get a little bit complicated.

Best Regards
Diogo