Hmm, while it would be a rather unusual way to do it "islantilainen mies on komea" could be understood as a general statement with the right context, but a better, more understandable way of expressing it would indeed be with a plural. However, a plural everywhere, rather than somewhere, might better describe it. ;)
"Islantilaiset miehet ovat komeita." - Icelandic men are handsome.