more surface area, as you suggested, would work.
The "barkiest" ones I got were cooked around 275F & I forgot to rub them until I don't remember how long they were on the smoker (might not have even rubbed, might've just added to the pulled product). They were probably 7-9 # each & IIRC, finished in 10-12 hours. My memory is sketchy but I remember thinking how strange it was.... in a good way. I always (almost always) run a dry water pan.