Gijon - Alicante driving advice please

Hi all, I hope you seasoned travellers/drivers can advice me about the best route to take from Gijon (N Spain) to Alicante via Villahermossa (west of Albaseta). the main criteria is the LESS hilly/mountainous road the better, i will be fine with Tolls, however long it will take as will have three days to get there. I am thinking of camping on route again any good safe sites will be greately appreciated. I will be travelling around mid-Oct.   many thanks