All, thank you for your thoughtful and informative replies, much appreciated!
We did take the Senda Litoral, and it was windswept and lovely coastline. Although I checked the weather in advance, there was a heavy wind from the north and that took some energy.
Alas, my Wise Pilgrim app (well, the map part) went belly up, so I was without a GPS (others are using Camino Ninja, which I downloaded tonight). We saw two faint yellow arrows near Viana de Castella, ended up on a stretch of N13, and asked some women with a fish cart and a police man, who pointed us the right direction. My fears about the path being covered by sand (per
Brierley) were not warranted. There were two sections that had some sand over the boardwalk, but that part was fine...
HOWEVER, no arrows, just an *very occasional* stone sign with Litoral Norte. At one point (halfway?) the path past the Litoral Norte stone sign was overgrown and we had to take a detour on a cobblestone side road. All of this was on the faith that we were headed north (again, might have been better if we had a GPS app). We saw very few pilgrims after the halfway point, or many locals, either. We also ended up on a sandy trail around a bluff around Afife and I was sure it was wrong, but my husband kept swearing he saw footprints in the sand.
We planned a 9 mile day, but walked 13.5 miles (including a bit around VDC, trying to figureoout the way and what to do) Forgive me for not adding the km conversion...it was an exhausting day, after the previous route from Esposende!
We eventually saw an arrow before Vila Praia de Ancora, and laughed out loud.
If you decide to take this route, definitely take ample food and water! We saw a restaurant a bit before Vila Praia de Ancora, but that was it. There are no houses nearby and it is a bit of a trek to N13 ( I think that would be the bail out plan?)
This was the first day since Porto that I would call an adventure.