Get her to do something really kinky that doesn't involve dick then?
Find a fetish, and get her into that... Say fucking herself with fruit, or something like that, but... well... better...
Find a fetish that isnt covered that well... You'll probably find that where it is covered (Whatever the fetish is that is) That the people doing the fetish, are older or uglier...
Then corner the market in that chosen field with her as the cutest girl, providing the specific fetish that has been chosen... Turn her into the 'Poster Child' for that specific fetish...
The above may sound silly, but its better to corner the market in an extreme micro niche, that it is to talk her into a Dick up her ass, have her not really enjoy it, and then go up against EVERY OTHER girl in the world that takes it up the shitter, but DOES ENJOY it...
The only hard part is to find the fetish... BUT... Find the RIGHT fetish... And your laughing!!!