Butts look at meat smokers and say "Bring it on baby! I can handle ANYTHING you throw at me." They are the most forgiving cut of meat you can smoke at any temp.
A couple times now I've done 18-20 lbs of Costco boneless butt (total weight, 2 in a package) in 9 hours at 300-325F chamber temp. Turned out great, nicely barked. Wrapped one batch when it first stalled and got a softer bark. Wrapped the second batch (and later single batches) at 170F and got a great bark. That's my go to method now. Once it is wrapped you can actually crank the temp up to 350 or more. The connective tissue still melts and the PP turns out juicy.
The issue with the Kettle is the distance between the top of the lid and the grate. You can have temperature variances of 80-100F the hotter you smoke between the top and the grate because the distance is so short. The boneless ones would help because they lie flatter (don't tie them up). Just flip them after 3 hours or so. Also, if you can build your fire to one side, put the meat on the other, and the top vent opposite the fire, you get better circulation.
There are a lot of ways to cook and smoke on a Kettle. Since you are pressed for time, hot n fast is the way to go. The Minion method works best for low n slow. A Weber grate with the flip up side makes adding charcoal a piece of cake when you build the fire on one side.
Save the juices from the wrappings, let them gel in the fridge, get rid of the fat (save it for other cooking actually) and put the gelatin back in the meat when you are ready to re-heat it. Pure flavor.
Congrats on the 25 years for the shop!