I walked the coastal camino this month up to Caminha, and then we (father & brother in tow) deviated inland from there. Here is my list of accomm and distance walked each day... Christian's list was super helpful as well as 2 sites I'll link to at the bottom. It's definitely do-able, and we likely wouldn't have had to take any transit had we been less particular about our lodging.
Lisbon
*Nest House Hostel (hostelworld)€18 with breakfast
Porto
*Garden House Hostel (hostelworld) €20 with breakfast
Day 1: (metro to Matoshinos + 24km walk)
Vila do Condes
*Santa Clara Albergue €7.50
Day 2: (Bus to Apúlia + 6km walk)
Esposende
*Hostel 11 Eleven €10 or €12.50 with breakfast
Day 3: (15km + taxi from Castelo do Neiva)
Viana do Castelo
*Pousada da Juventude €10 with breakfast
Day 4: (10km)
Carreço
*Casa do Sardao €12 walk-in or €14 booked on Airbnb
Day 5: (10km)
Vila Praia de Âncora
*Hostel d'Avenida €10
Day 6: (13.5km + train from Seixas)
Vila Nova de Cerveira
*Pousada de Juventude €10 with breakfast
Day 7: (20km)
Tui
*AlbergueTuiHostel (booking.com) €12
Day 8: Rest
Day 9: (18.5km)
O Porriño
*Alojamiento Camino Portugues €10
Day 10: (15km)
Redondela
*Albergue A Conserveira €10
Day 11: (7km)
Arcade
*Albergue Lameiriñas €12
Day 12: (11km)
Pontevedra
*Aloxa Hostel €12
Day 13: (23km - used backpack transport that day)
Caldas de Reis
*Hotel Balneario Acuña €40 with breakfast and thermal pools
Day 14: (9.5km)
Valga
*Albergue de Peregrinos de O Pino €6
Day 15: (9.5km)
Padrón
*Albergue A Barca de Pedra €13
Day 16: Rest
Day 17: (17.5km)
O Milladoiro
*Albergue Milladoiro €14
Helpful Resources
Distance & elevation:
http://caminodesantiago.consumer.es/los-caminos-de-santiago/portugues/
Distance & lodging:
https://www.gronze.com/camino-portugues
Bom Camino!