not sure how large you are talking about, and is it a film (moving) or still (slide) projector? You might use a piece of scrim and project on that. Depending on where you want to set up, and again how large, you can use plexiglas and do it sort of like a peppers ghost.
"Project" water under the head! There you go! It's floating!
Or put a beanie on the head with a turning prop on the beanie and the noise of the projector could be the noise of the engine turning the beanie's prop!
Sound and motion all in one effort.