Take two levels of rogue and do Thief-Acrobat for five levels. Take the Quick STaff style from CW, and Two-Weapon Defense. When you fight defensively, thanks to TWD, tumbling, thief-acrobat, and the style feat, you'll get something like +9 AC over just your armor, plus any Combat Expertise you use.
Forget about a martial quarterstaff. You'd be talking about a single point of damage, and your weapon would be difficult to upgrade since it's not a common weapon. With four levels of fighter, you can take Weapon Specialization, which gets you +2 with both ends. And you can build up your TWF chain to get as many attacks as possible.
After Thief-Acrobat, go to Tempest to pick up some more defense, some more two weapon tricks, and stay with your light armor theme. You'll pick up +3 AC in light armor and your TWF penalty will be zero.
That puts you at Fighter 4/Rogue 2/Thief-Acrobat 5/Tempest 5, which leaves you four levels to play with and only a three point BAB ding.