[MetalMan]

How would a 10XL on 6s Lipo sound to you? You could get either two 3s 8000mah packs (4000mah cells) or two 3s 6000mah packs (3000mah cells). Both should/would work, but the 8000mah pack would obviously be more expensive.
Or, depending on your chassis balance, you could go with a 9XL on 5s Lipo, and have the 3s Lipo pack on the opposite side of the chassis from the motor to sort of counteract the weight of the motor on one side. The same cells/capacity apply.
Then you could get a Hyperion balancer (or two, depending on how you set up the batteries). You could get one balancer if you do what I did to my 4s pack (two 2s packs); wire one pack up with the balancing plug, and have plugs on the other balancing wires that plug into the other pack (kind of confusing, I know).