Wharvey, hello brother. Just a guess, but I'm thinking about 6-8 hours at that temp. Just in case you did not know, if you're cooking that low and slow, you ought to expect to discard the skin as it will be decidedly inedible.
That's not always the case, actually. While a lot of the time smoked turkey and chicken skin is rubbery, you can sometimes crisp it up by raising the heat for the last 30-45 minutes. I do this by moving the bird closer to the SFB vent on an offset smoker, or by draining the water pan on a vertical smoker.
And just as proof (before anyone argues), here's one I did last year. It's a big 4 1/2 pound free-range chicken that took about 4 hours to cook at 275F, including the 45 minutes to crisp the skin. I popped it right over the SFB vent to finish it and took it off at 160F internal temp:
The skin on this beauty was as crisp as if it had been oven-roasted, and the meat was very moist even without brining (which I personally find to be a bit overrated at times). I hope this helps.