Long term parking in Santiago

Hola
We are returning to The Via de la Plata in September to complete the walk from Seville, we have about 100 miles left to do which hopefully will take us about 4-5 days. We are planning to take our camper van to Santander on the ferry , drive to Santiago park up then catch bus/train to where we need to start our walk. Does anyone know of anywhere in Santiago with safe long stay parking and the cost of it ?
any help/comments much appreciated
Clare

Thanks Falcon269 for the link, looks like there is parking right at the train station which will be perfect