Hard to tell what the SB is doing. Who caps the flop and check-calls the turn except maybe a weak 8? Wish I had more experience to know that answer. I think even an A28x would have to lead out on the turn right?

Even if your A2 is still good for the entire lo (which I actually think it may be) you are still on the draw and I'd be suprised if it didn't get capped behind you. I'd definitely just call too and hope I had enough good karma for an Ace on the river...