I've found mopping & moisture make a big difference in the outcome of the surfaces of my smoked poultry and 'small' meat (such as ribs). After the meat's been on 90 minutes or so I mop roughly once or twice per hour, depending on weather (less in cold weather) and on what seems to be working. And I do like a drip pan full of liquid (beer, wine, vinegar, water, apple cider, etc) as my baffle; the additional moisture keeps the surface of the meat or poultry from drying out.
Posted in another thread that a few weeks ago I tried the no-mop method on a couple chickens and the meat was delicious but the skin leathery. So I'll sacrifice an extra hour of cooking time to get the results I want.