Let's assume Persistent Spell does not exist, but all other first party material is allowed pending DM approval.
I was considering going Dragonborn Fire Gray Elf Martial Conjurer6/Crusader1/Spellsword1/Jade Phoenix Mage5/Abjurant Champion5/Dragonslayer1. I get 16 BAB and base caster level 18.
Feats, skills, and spells gained each level are still up in the air.
Persistent Spell, however, is a great draw. If I could, I would go Incantatrix3 for Metamagic Effect, but such is not to be.