Hi Courtney!
Yes I think so but it depends on you, I walked from Penefonte 10km AFTER Grandas de Selime to Santiago in 7 days, but some of the days were quite long. My stages were this:
Penefonte to Padron 18.7 km (from Grandas de Selime 28.7 km)
Padron to Castroverde 29.2km
Castroverde to Lugo 21.5km
Lugo to San Romeo de Retorta 19.1 km
San Romeo to Melide (Back on
Camino Frances) 30.1km
Melide to Pedrouzo 32.8km
Pedrouzo to Santiago 19.8km
Easier would be from Padron or Castroverde in my opinion unless you are confident with these type of distances. Very doiable would be from Lugo but that is only two days walking on the actual Primitivo before it joins the Frances.
Or, for the best Primitivo walking why not start in Oviedo and walk one week? You will get the best of the Primitivo that way (The Albergue at Bodenaya, Hospitales mountain route and around Lake Embalse de Salime ending at Grandas de Selime (do the rest later)! That is what I would do if it was the Primitivo.
There is always the Camino Ingles though, a full route to Santiago!
Enjoy!
Davey