Well, I think Purple Chick's "Mrs. O'Leary" proves that the "Fall Breaks" vocals are a good enough fit.

Wouldn't it be magical to be there when Brian suddenly sings what you recognize as a different (but similar) Beach Boys song.... and you realize that the missing piece of the puzzle is in place?
I mean, this might've just been from BWPS being my primary introduction to the Beach Boys' catalog, but hearing "Fire" without the vocals just seems, to steal a term from George Harrison, "so... naked!"