You know Chris, this is exactly what I went through when I first got my WSM. Larry R, tried to explain to me how to do an overnighter, and I just struggled to get mine to maintain a steady temperature. I even went to the extent of taping my door shut with heat tape, and still struggled. I got lots of advice, and was very close to just saying the hell with it. Then I checked into a power draft system. When I got it, I set the temp for 225* at the lid and 190 for the meat. I put my butt (pork butt) on at 10:30 pm as well, and I went to bed. I had all of the bottom vents closed and the top was just barely opened. I woke up the next day at 5am and once got my eyes adjusted I decided to venture into the backyard and check in things. My pit temp was sitting right at 225* exactly where I set it the night before. It ended up being a 21 hour cook and I couldn't be happier. The only time I don't use the power draft system is when I am doing chicken, and that's only because I cook the chicken at a very high temp and it's not on there as long either. I have to be honest with you; I never thought I would take a chance on something like this, but I sure am glad I did. It's too easy... yet you still will enjoy the challenges of creating good BBQ for your friends and loved ones. Larry R. uses the Stoker while I am using the DigiQII. There are lots of people that don't use these systems and have tremendous success with their cooks, but since no two cookers are the same, it's a very good alternative especially for people like myself who don't have a lot of patience when it comes to adjusting vents and trying to stabilize temps.
Good luck with your cook(s)...