Mind you, I dont live in MO (snow & all), but I dont have to babysit too much, even though I use an offset. I'm thinking you may be doing a few other things less-than-stellar that may be hampering your efforts.
That aside, way back when I had a much smaller offset and could only cook 20-30 lbs of meat at one time, I used a trick to help. Shhhhhh. Be quiet now. Dont tell anyone. It's called an: Oven. Yep, put the meat on for 3 or 4 hours on smoke, then bring it in, foil it up, put it in the oven for the remainder of the time. Side benefit, the house smells like BBQ. I still do this for smaller cooks when I want fresh BBQ at 9am in the morning. I'll put it on smoke for 4 hours, take it off around midnight, foil it, in the oven it goes and shut-eye I get.
No need to spend extra money.
Hance - Lake Dogs Cooking Team - MiM/MBN/GBA CBJ and comp cook
Lake Sinclair, GA (strategically about an hour from everywhere)