Damn Zip-Zag that is a great mount!!!!
I will post a pick in a bit, I have tried angle iron mounted to windscreen brackets which was too woobly and then a piece of square aluminum tubing mounted on the windscreen brackets and it still shook. Then I put the extra heavy springs on the windscreen brackets and that helped, it will work, but drives me crazy with wiggles and bounces at slow speeds.
The bar mounts are the only way in my mind and your bracket gets the GPS up high and more stable than the 'dash mount',
PLUS love the price of this fix !!!