Interesting idea. I think breakaway mirrors are a great idea. Why not lights? They're more expensive, after all. I had something of a folding bar on my Strom. It saved the lights in a couple of falls.
How are the joints made up? How do they stay rigid at high speed? Bear in mind, these are GS riders; some people have 7" or larger diameter lamps. That's a lot of wind-catching area. Aluminum may bounce/vibrate, too. I haven't had good luck with aluminum light bars.
If that becomes a problem in testing, maybe you could have a spring hold it in position. Also, maybe a shape on the end of the lightbar to guide it in the right direction would help guarantee it folds in correctly. Like a half-moon horn on the end of the bar.
Just my musings. Good luck! If it pans out well for you, I hope you develop it for other makes, too. The fall down test video will be the proof