Will ABV boost from barrel aging cause bottle conditioning concerns?

[wickerman]

Any way to tell/guess how much abv boost you will get from barrel aging? I’m planning on doing ~15 gallons of bourbon stout (in a fresh 15 gallon barrel) with a friend. I’d imagine 10, if not all 15 gallons will be bottle conditioned. I keg, he doesn’t. Plan on giving a lot of it away too (if it turns out well). He’s gonna wanna make it big, but I’m concerned that it’s going to have trouble carbonating w/ the extra alcohol added by the barrel. Any advise? I mostly make sour stuff, so the ol’ champagne yeast to carb trick comes to mind, but I’m not sure how that works in a stout. There’s usually no sugar left at all when doing that with a sour.
Or maybe I’m just over thinking the whole thing? The surface area to liquid ratio of a 15 gallon barrel is just so much higher than the 53-60 gallon barrels they tend use in breweries.

Thanks,
wickerman