Touring Spain and Portugal

DLR

We are going in September for a few months.  Starting at Bilbao we plan to follow the north and west coasts then  down the coast through Portugal and then to the Seville area and return through the middle of Spain via Madrid and Santander.

We are researching of course but you can't beat actual experience - if anyone has done anything similar and could suggest routes and in particular campsites that would be so helpful!  

We understand a lot of sites close or are open perhaps just at weekends when the high season finishes.  If anyone can recommend sites which are open all year that would be good.

Many thanks in advance!