During my trip through Portugal from North to South, I tried to follow the coast as much as possible for several reasons : fewer hills, more cycling paths and more campings that would be open in the low season. Campings located close to popular beaches are often too big and not very attractive. The worst place I camped was on Parque de Esmoriz in Esmoriz:
Tightly packed caravans, fences, lights, concrete paving and guards walking around day and night. It feld like a prison camp and I was happy to be released from this place in the morning.
Orbitur https://www.orbitur.pt/ is a chain of campings that are usually open all year and offer a bit more space and vegetation.
Below are some other nice places in Portugal that I can recommend :
Cepo Verde : nice terras camping in Montesinho nature park in the North with a good restaurant and a nice swimmingpool.
Camping Coimbrão : This camping is run by a friendly Dutch couple who keep everything exceptionally clean and well organised.It is located a bit inland and open most of the year. There is also a swimming pool.
Parque de Campismo Sao Jacinto : on a land tongue just a few km from the village where you can take a ferry to the main land. It has a nice area for pitching up a tent and Eucalyptus trees.
Parque de campemismo de Quiaios : spacious camping with pine forest close to the beach.
Parque De Campismo São Miguel : it was strange to be in this luxurious place with a big restaurant, supermarket, swimmingpool etc. all fully operational in mid October for just a handfull of guests.