If you do use your rear turn signals as running lights, or even as stop lights, you'll need to change to red lenses.
Harley actually sells a replacement control module for their late model bikes to do just that. You replace the lenses on the rear signals with red, and install this module, and the turn signals become turn/stop/tail lights, in addition to the center-mounted tail/stop light. I did a trip with a friend who was riding a 2007 Sportster with this setup, and having three stop lights really makes it obvious when he was braking.
While you are at it, you could try to also add hazard light function, which, IMHO, all bikes should have.