Chord Swaps

I realized that if you superimpose the IV and V chords in a key, you can easily flip their function by swapping the bass note: Key of G: C becomes the dominant when D is in the bass (C/D, or D11) and D becomes subdominant when C is in the bass (D/C or Cmaj7#11). The typical 70s singer-songwriter sound (Elton, Carole King)