You can cut it in half. It will add more bark, as you said, and probably shorten the cooking time.
But I gotta tell ya, there is something about cooking a butt for 12+ hours that just can't be beat. The process of building the fire and getting your cooker to cruise at the right temp (225 for me). I have a routine of starting my fire at 11pm. I get the butts on the smoker at midnight. Then check the cooker every hour (yes, I enjoy it) through the night. Usually settle in to sustained sleep around 7am, knowing my kids will tell me if the temp gets too high/low (never happens). Usually sleep through the stall and wake around noon as things are finishing. Depending on the size, pull between 1 and 3 pm. Wrap in foil and place in a cooler until 5pm. At 5pm, I pull and hit it with your typical no. carolina sauce. Family loves it, and it feels like 12 hours of time well spent.
-elbows deep in someone else's misery.