Question is...why are you losing 4 caster levels? Your aim should be to take the bare minimum in order to get into a Gishy PrC like Abjurant Champion or Spellsword or even Eldritch Knight or Knight Phantom.
Its going to be a gish, leaning more towards martial. Trust me, I've been over this about 400 times in a different thread haha. And I'm actually going to be doing AbjChamp and Spellsword. But what is this knight phantom, and where can I find it?