My dogs (airedales) love beds, quilts, sofas - anything soft.
I think quilts would be good.
Another idea, since you live in cool climate, would be to decide definitely if the dogs are small, medium or large and make them a dog coat for the winter. The main part could be a quilted back. That part would be oblong. Then put straps to go under the belly in two places and one from shoulder to shoulder.