I was just thinking of this, I was considering to maybe making a metal arm from a piece of conduit for a streetlight. Maybe around 1 1/4 inch diameter should do with a bender. Would it work, or would it not work, because EMT conduit is a bit stronger (correct me if I'm wrong) which could hold the fixture's weight. Just saying, its a good idea.

I would be concerned about it bending if you use an extra-heavy fixture, but it would probably work for a little one.