Hi Louis,
Great that you already have been working on a proposal.
Let me explain how mentor assignment works during SoC. A student work on his/her proposal. If he/she wants input before he/she applies, then the forum or this maillist is the best place to discuss your progression. In this stage every involved mentor can reply and provide you with feedback.
Just make sure you apply before the deadline of 31 March. After this date the mentor organization will start ranking your application, and if needed discuss it in more detail with the involved student. It's in this stage that a mentor (or more then one) is assigned, not sooner. If a possible proposal is interesting it can happen that a mentor already pre-assigns him/her self, for now that has not yet happened.
So what I suggest is that you apply with your proposal so we can study it, rank it and preferable select it as one of the projects for this year.