John- I have a variety of neglected apple trees that you are welcome to look at. We probably need Stu to tell us how it should have been done.
I don't know about Missouri weather, but I like some trees on a gentle north slope and some on a gentle south slope.
North slope trees break dormancy later, and bloom slightly later. That might protect them from a late frost.
In Minnesota, I just mix the crabs in with the apples. Hell they are all apples anyway and the deer don't care if they are bigger than 2 inches or not. Actually, I think they prefer smaller apples that are bite sized.
I have been trying to keep an eye on CAR, but you should have far more choices of varieties in your climate than me.