Focus BIF using 7D

I haven't had my 7D very long but want to try shooting some BIF using this new AF System. My concern is using AI Servo as a bird flys R to L under low-light (wide open ap giving shallow DoF). What AF System or technique should I use to prevent from locking focus on the closest wingtip resulting in an out of focus bird?

Use single point spot focus and keep it on the birds eye, easier said than done in practice though

I have trouble just seeing the bird is the VF so trying to focus on the bird's is way beyond my ability....I better just sell this while I can.

To be sure it is not easy. BIF is one of the most difficult things to shoot well and consistently IMO. Small dogs running full blast is similar. The guys that do it consistently have an under-appreciated talent.

Single point or single point with expansion, limited experimentation so far suggests that area focus tends to lock on to the wing tip although if the bird is close enough the area might only cover the head and be OK, but in this case I would think the bird we be to fast to get a lock.

Thanks to all,
I will do some experimenting this weekend. I added and enable AF point expansion (C.Fn III -6) and slowed the Servo tracking sensativity. Then with AI Servo set and 8 fps I will see what I can bag.

Is there anything else I'm missing ?