I tried this conversion when I first bought my 08. I used LED bulbs in the marker lights and was not able to see them flash with the stock headlights on. I added a HID kit and they completely drown out the visibility of the marker lights flashing. Finally I opted for a one off set of block offs with the signals flushed in them. Greggs Customs makes a set of block offs with signals - check them out if you are planning to go mirrorless.
Outside the US, Kawasaki sells a cool-looking "micro trapezioid" LED replacement signals for the bulky 2008 stock incandescent units. Just have to figure out how to get it into the US since I can't actually find it for sale on any website. Does anyone know how to get these?