Your biggest problem is lack of chill-hours. One of the few drawbacks to living that far South. However, it seems like I've seen some of the California fruit growers on the Fruit & Orchards forum indicate that they can get fruit from apple trees that the experts claim *shouldn't* bear, based on their chill-hours, so it might be worth visiting over there and emailing one of them(I can't recall for sure who it was - probably calistoga, pitangadiego, or joereal - one of those folks can probably put you onto the right track.).

Lady Williams(a seedling of Granny Smith) and Centennial crab both do well at my parents' home just outside of Auburn, but I don't know how they'd perform at Mobile. Both are nice, tart, apples.