I'm considering buying the SW-Motech rack to be used with the ortlieb soft luggage. But I see in the installation manual that on is supposed to use an extension that follows to move the blinkers farther back. Is this really necessary? Doesn't seem that this is needed on the touratech racks for example. I have the LED blinkers by the way. Does any one have any experience with the SW-Motech racks?