I called Performance Bicycle and they told me that it should work as my Ergon grips do not have the extension - so I went ahead and ordered it. It looks like I just have to pull out a plug at the end of the grip to install the mirror.
I don't know what else I CAN get for Stella, she seems to have a full set of accessories outside of clipless pedalsI want to get some miles on her before I decide on whether the saddle stays or not.