Like Dude said, cook the apples first.
Apples take quite a bit of time to break down to a softer texture so they are best cooked first and then added to a fattie.
Peaches would be fine to add in their natural raw state I would think because they are quite a bit softer than apples and will absorb heat better and break down more easily.
You could always wrap in bacon and coat the bacon in a brown sugar or brown sugar mixture to give it a nice and sweet crust.
With peaches I would try a sweet sausage or a maple or regular with a sweet smoke and add the peaches (cooked or not) in with some form of a cream mixture/sauce. Maybe a sweetened mascarpone or sausage with peaches inside, smoke over a sweeter fruit wood. Pulled off the heat, cooled slightly then wrapped in a cobbler type of dough, baked then sliced with a nice cream sauce or whipped cream over top.