This sounds like a great idea. Left-handed folks aren't the only ones who might appreciate this.
Don't own a dedicated flash unit, but fortunately all of the potato-masher Metz flash units allow you to reverse the mounting bracket, putting the flash on the right hand side. For awesome lighting effects, two flash units can be attached to the same camera, one left, one right. However, feeling creative and adventurous, I tried this with my medium format SLR, a Mamiya 645. I got results, but with the weight of the 645, plus lens, plus motor, plus two Metz 45CT-1s, it felt like I was lifting a moped engine in front of my face!