Hi Doug,
10/11 full days of walking from Ribadeo is very doable, there are no real hard ascents or descents and in your face terrain. The longest stretches without places to stop were Mondonedo to Abadin and Miraz to Sabrado dox Monxes, for this latter stretch there was a non advertised little shop which had unusual hours of opening about halfway. However your biggest problem is the amount of other pilgrims who will be walking at that time of year, this far exceeds sleeping capacity, and I have heard of instances of it getting quite fraught in some albergues as people arrived later to find no space. You can overcome this problem by staying in the few private Albergues, they take bookings in advance or only walking short distances and arriving at the other albergues early to take your place in the queue. There is the hotel and pension option, I know Ribadeo, Villalourenza, Mondonedo, Villalba, Sabrado and Boimorto have options of this nature and probably a lot more places that slipped under my radar. Check the Eroski websites for comments on the albergues on the Norte, this often tells you the troubles that people have in finding space at this time of year and also it can give you usefull tips about other options. When I walked this stretch in July 2010 I kept hearing instances of sports halls being opened to pilgrims, Ribadeo was one and Boimorto was the other, so where ever you go always check in with the local Tourist info people they may have heard of something which has not filtered out into public knowledge yet.
Good luck and buen Camino
Mike