It's well-known that a subject complement can be a noun or an adjective. It's not hard to make out what part of speech the subject complement belongs to— For example, in He is a pilot and She is beautiful, it's easy to say that the subject complement is a noun and an adjective, respectively.
But is this always the case? What about the sentence—
Outside is a hawker.
The subject of the sentence is hawker and it's apparent that outside couldn't be a description of the hawker, and so it can't be a noun. The possibility of its being an adjective is also ruled out because it doesn't "modify" hawker in any way.
Could it be that the sentence is actually an abbreviated version of On the outside is a hawker?
This seems to make sense because here the NP the outside could be serving as the object of the preposition on.
Is that right? Or am I confusing things here?