I am a girl rider as well, and personally, I would not do anything to purposely make my bike look like a girl's bike. When I ride, there is no doubt I'm a girl (body shape, gear to some extent), and that is enough for me. If anything, I wish I got a lot less attention (same as CBRsexyRR).
I find it way more interesting when a woman rider has a bike with mods that are typically associated with serious and knowledgeable male riders.
I am not looking for people to know I am a girl riding - because that as you stated is clearly obvious! Granted, I stick to typical male styled gear, because I have broad shoulders and have no luck with the girl ****... however, even with such, my body shape is feminine all the way... there are some things you can't hide under any jacket...
The mods that I have done look great, I think... And I get a lot of compliments on it... Even my friend that helped me with the mods commented on my taste :)
However, with that said... I am not looking for attention, because I get that no matter what - as you girls know... But at the same time would like to change it up a bit... if my bike is in the middle of 100 bikes, yea, I would like it if people around saw something to trigger it being a girls bike, because then it makes the other mods that much cooler :P I think....
But I seriously cannot think of a single thing to achieve that... however, I like the idea of using something I would have a tat of - because when it comes down to it, that would be feminine :P (or not...)