Hola
@Krieg01, As J Willhaus advises you will definitely encounter significantly more pilgrims by following the Camino. Yes your idea of following the walkers might be more interesting but in reality (imho) the last 50/60 KM does not have much of significance.
When I cycled in 2015 (Sept and a week in Oct), I followed the pilgrims but often it was more than a pain!
So I suggest you do this:
Leaving Sarria follow the LU633 (or the C535 - I think its the same road).. About 6 km or so you can take a minor road to the right - it will lead you to Morgade (check your regular camino guide book). From there you can follow the yellow arrow all the way to Portomarin. From there to Palas de Rei the yellow arrows will take you past Gonzar (again I think this is the LU633). The Camino virtually parallels this road to Palas.
If I remember correctly from Palas I tried to follow the camino path towards Melide but gave up and resumed riding the minor road the again tracks the camino.(I think its the N547. Around the Santiago Airpot I picked up another minor road that the pilgrims were walking on. It took me virtually all the way into Sanitago. Do stop at Monte del Gozo, you might need to walk of track about 1 km to your left (south) to get the best view of the city and the Cathedral. Take it real steady coming down from Mt Gozo the road will be packed with walking pilgrims who wander along like lost sheep.
Hope this helps. Cheers