Canoejack,

Thanks for reminding me of that old baked apple trick.  I haven't done it in the Q, but I might next year.  We used to do them as kids on family camping trips and in the fireplace at home.

A couple of other related hints:

Try to wrap the foil in such a way that the foil is your bowl for eating the apple.  Make sure you can easily unwrap without tearing up the foil too much.

Sprinkle the inside of the apple with cinnamon before you put the other stuff in.  Also a tablespoon or two of raisins inside also adds to the flavor, if you have them along.