mixing all grain with fruit? apple bourbon

[Spamgel]

while getting things set up for my first all grain attempt my nephew stopped by with some apples. so of course I start doing the math in my head for a calvados. then I got thinking. why not add some peeled and cored apples to the bourbon mash? I am sure this is not an original idea, has anybody tried and have a good balance between apple and whiskey? For a 5 gallon recipe I was thinking of adding 8 pounds of apple to the pot, that should be roughly like adding 2lbs of sugar for specific gravity but hoping it will not over power the bourbon taste.
Just wondered if anyone has tried this and could recommend what would be too much of something.