Could this helicopter's body be a flying wing?
No, you need sufficient wing span to produce lift without excessive induced drag. 

Lifting bodies are only a thing of hypersonic flight where the induced (component of wave) drag is tiny compared to the form (component of wave) drag.

Induced drag is an unavoidable side-effect of producing lift over a finite span. It decreases with wing span, and with dynamic pressure (which in turn grows with density and square of speed; indicated speed is a square root of dynamic pressure). So at slow speed, you need considerable wing span to generate lift efficiently. This applies also to helicopter rotors, which is why they have such large diameters.

Since the other component of drag, form drag, increases with dynamic pressure and cross-section, the optimal wing span decreases with speed. But even jets still have quite high aspect ratio (square of wing span to wing area). Flying bodies without much any wings only become efficient well into supersonic area—and keep in mind that anything resembling a propeller (including tiltrotor) is limited to subsonic.

(At supersonic speeds, the mechanism of drag creation is different, called wave drag, but it still has a form component and induced component and the induced component still depends on wing span and dynamic pressure in the same way.)