Just a suggestion. I pretty much do the exact same thing as this, but using sugru. You'll find that you will get much better results with significantly less work. Everything you did to modify the plastic mount itself you still want to do. For the sugru, use two packs of sugru and combine, plop it to the front (this is the technical terminology), and stick your mount into it and compress. Use water to smooth it into the desired shape that matches the contour of your helmet.