They are a beautiful thing when you pull them out of the smoker, aren't they?
When I smoke a butt, I rub it the night before and put it in the refrigerator. The morning dance is to take it out of the fridge so it can warm up a bit, then get the smoker ready and warming up (also a 30" MES, but the one with the controller on the top in the back). Once the smoker is at temp, I put the butt in the smoker. The butt barely warms up at all before hitting the smoker. A few weeks ago, I did a bone-in "picnic", which is like a Boston Butt in being a shoulder, but has some of the upper arm. Also around 8 pounds, if I recall. It was done within 11 hours.
But a bow to your toughness for sitting up all night with the smoker, though. With my wife, when I tell her I'm going to smoke something, she expects it to be done by Her Dinner Time, and it's up to me to start it in time. If I were to do a big brisket, I'll probably need to start it at midnight so I could smoke it 'til the next night at 6.
This Monday, I did a small brisket flat. It was under 5 pounds, so I figured it would take five or six hours. Had it in the smoker by 6:45 in the morning and figured it would be done by 1. No such luck. Even though it was only a 4.5 lb. flat, it took until 5:30 PM for the temp to get over 203 Internal Temp. Let it rest for an hour and it came out great.
Bob