I am walking now, left Saint Jean April 2nd, and have had little problems with being warm enough. Granted, I tend to not mind the cold as much as some, but I do have circulation issues and have been ok. Almost everywhere I have stayed has had blankets, some more effective than others. The only place I was really cold at night was in Boadilla (stayed at En El Camino).
Worst comes to worst, you might have to sleep in your clothes one night. Compared to carrying an extra 1.5 kg on your bag (after deducting the weight of a silk liner bag), this seems like a no-brainer to me. But then, depending on your age and back condition, the weight may not be such a big issue as it would be for me.
Anyway, my .4 nickels (Canada did away with the penny a few months ago.
)
Glen