Thanks. Considering the Central Portuguese someday, just apparently lots of road walking. Anyhow, that’s exactly what I see on MAPY.CZ. The Senda do Louro Mos appears to be the river route (Chans) Brierly mentions but only starting at Camino da Gata (N42.1921179° W008.6093314°) and ending at Estrada Puxeiros - Mos (N42.2043634° W008.6040203°). Maybe the main route here, albeit more road, would be fine.I tried finding the Chans option described by Brierley in his Camino Portugues guidebook last year. It doesn't exist, certainly not as described. I ended up following a mix of the N-550 and some minor roads until Camino da Gata, and walking west from there across to Camino do Castro where I rejoined the waymarked route into Mos.
Open Street Maps shows a path along the Rio Louro labelled Senda do Louro Mos. I did see the southern end of this just after Camino da Gata crosses the Rio Louro, but I had already spent some time unsuccessfully trying to find the start point for the path described by Brierley going north from Camino da Serra da Auga, so I wasn't inclined at that point to undertake any more exploratory excursions.
The marked route is on fairly quiet roads, albeit they are all sealed from memory. Only later in that stage is there some relief. Unlike the two other complementary routes, before Porrino and Pontevedra, this is not an alternative I would recommend, at least not for the faint hearted. Even the short stretches of the N-550 that one needs to walk along aren't pleasant compared to the alternative of the much quieter country road used by the marked route.Maybe the main route here, albeit more road, would be fine.