I’m from Porto, North Portugal and this could be a nice start to you. You have many free places to spend the night with beautiful views, a great city to visit and enjoy. You also have good beaches all around just need to choose if you want to go to a busy city beach or a quite natural beach, between Matosinhos and Gaia!
If you start to go down the coast you should stop by aveiro, the Portuguese venice, and have some ovos moles, a traditional pastry really nice, also the beaches are really nice around there and many places to camp around.
After these you can make a stop in figueira da foz, another beach place quite and beautiful.
A little bit more down and you have Nazare, the biggest wave in the world and a great fisherman’s village to walk by and camp. About 60km after you have peniche that is also a fisherman’s place and the Portuguese waves capital!
A few km after you can find ericeira the unique world surf Reserve in Europe and after you have Lisboa, the Portuguese capital that is a must visit too. In the meanwhile you have mafra with beautiful landscapes and castles.
After lisboa you have sesimbra and Sierra da arrabida, also a must check and if you live the ocean and mountain these will be a perfect spot.
Still going down and you can visit troia (ok, this is a fancy spot) nothing to see but nice beaches and views to Sierra da arrabida.
After troia you can begin the tour threw the vicentina coast, for me the best place in portugal to vanlifing! Each small village as great beaches, parking spots, camping spots and crystal clear Atlantic water! Make several stops along the way and I am pretty sure that you will be amazed in here. My favourite place there till now is monte clerigo, quite and nice!
After this coast you will begin the Algarve coast, this is touristic but there’s still many places to visit like sagres, portimao, faro, tavira or closer to spain vila real de Santo antonio.
Hope this would help you. If you have any question feel free to be back to me!
Cheers mate and enjoy the road!