Hi i did this stretch in mid july, there is a tourist alburgue in Esteban de Pravia which is about 23.5 km from aviles, im not sure of the address, but a few people who stayed in Aviles and Soto de Luina at the same time as me said it was okay and clean. A lot of the spanish and german people stay there because its in their guides.
I stayed in Muros de Nalon in a tourist apartment(about 20 metres up the road from the supermarket which you can see as you get on to the road after coming off the bridge, going up the road, then the dirt track and eventually the main road again), they were 30 euros for a single person if there was two it would have been 20 euros each, and as there was a bunkbed in the front room, you would have been able to get 2 more people in, and probably haggle it down again.
If you do stay in Esteban de pravia its only about 17 km to Soto de Luina, however the potential for getting lost after Cudillero is high because of the new motorway they are building along this section of Austurias and at various parts it cuts right across the camino, i got lost but ended up at very bueatiful beach with a lovely bar cafe next to it(it added about 2km to my day). This crossing doesnt really happen again on the camino untill the section after Luarca on the way to Pinera(most people avoid this by using the provisional route which there are signs for).
The stretch from Soto de luina to Cadavedo is virtually along asphalt(about 22km out of 25km) its along the N632, which hardly anyone uses apart from peregrinos and cyclists. you need to protect the soles of your feet on this day. There is 10 beds in the hostal in cadavedo, i was very lucky and got one, 5 people slept in the kitchen area and another 5 people were taken to other accommodation were there was spaces, and i had the feeling if more people turned up they would have found space for them.Just a footnote to this stretch, is that the old camino used to go up to the top of a place called las Bellotas( i think) which is 720 metres high, its no longer open to the public because the path is overgrown, so thats why everyone is sent down the road. However on the day i did it, 3 young guys from Majorrca went the wrong way and ended up there, they showed the marks on their staffs with which they had to beat the vegetation and quite a few photos of big spiders. But the looks of happiness on their faces from the adventure and the views they had was in strict contrast to us who had walked the road and had the 'easier day' and were nursing various complaints with our feet.
Sorry to go on but i feel like that when i can go on about the camino,i do. It was my first one and hopefully not my last.
mike