You could cheat a little by using your Performer and the oven too. Smoke the butt for 4-6 hrs., then move to a half pan covered with foil in the oven @225° until it is done. I have done many single butts this way and it keeps you from worrying about maintaining your cooker temp overnight or what the weather is doing. Start it @ 10pm., pull it off the Performer around 2AM and put into a half pan, roasting pan with a rack, etc. and cover with foil. Put into the oven and let it go until probe tender.
This lets you get some sleep as a bonus. If it gets done early (for me, 8 lb. butts take 8~10 hrs. total cooking time), then wrap in foil and either place in a cooler covered with an old towel or two, or just turn the oven off & let it rest there. I try to raise the butt off the bottom of the pan a little with some sort of rack so it isn't swimming in it's own juices.
Good luck with your cook.
Traeger Lil' Tex Elite, WSM, Green SS Performer, 22" OTG, hyperfast orange Thermapen. CBJ.