There is a large meadow behind the albergue at Ribadiso, about 2km before Arzua.
I know - I've passed there twice and twice it was full ! OK, the first time we arrived about 7:30pm, so we really couldn't expect anything else! So I/we slept outside - once borrowing a poncho to protect my sleeping bag, but I now carry a lightish-weight bivvi at about 300g. I fully expect to sleep outside here again this summer when my Camino Primativo joins the CF.
Both times there were groups camped here - so they seem to expect and accept it.
Mike