First, you cannot split coils, but you can always ad a second PU if you carve/route for it...
Your next best options, as far a Alembic electronic is concerned:
Upgrade to a Filter + Q-switch (I would do that if I were you)
Then, further, I read about the East meet West circuit aka EMW
where in fact you use both, the Bass/Treble boost/cut as well as a Filter + Q-switch, but for that, you will have to have it done by Alembic, because it is not a straight forward plug'n play job.
But the Filter + Q-switch, you can order it, and plug it yourself in 5 minutes.
Let me know what you think...
BTW: Ask Chris aka Bumhucker what he thinks about it, because he did the exact same mod and he told me that he is happy with it.
In fact, I bought his Bass/Treble boost/cut left over...