That was definitely the right choice. Sparky worked great, but the 'cue turned out only slightly better than moderately good. Definitely not the best I've ever done. It was flavorful and wonderfully smoky, with a deep burgundy smoke ring, but large parts of it were tough, chewy -- plainly, it had not gone long enough.
I blame technology. I cook primarily by instruments and I used new, untried, uncalibrated, cheap probe thermometers. I need to invest in higher quality tech. The probes were reading 200+ degrees when I called it done, which should have resulted in fall-off-the-bone tender, sweet, lip-smacking meat.
For fuel, I used charcoal, spiked with hickory and pecan chunks for smoke production. I did a simple overnight rub on the shoulders, mostly paprika, salt, and brown sugar.
The day started early: I was out of bed by 6:00 a.m. getting things together. My goal was to have butts on the grill by 7:00 a.m. Alas, that proved to be fairly optimistic. By 8:30 a.m., I had finally hit the target temperature and the meat was on the grill.
And then I settled in for the long wait.
I have a small grill set up beside Sparky on which I kept a chimney-starter full of live coals ready at all times. I replenished the coals and smoking wood about once an hour, on average. I kept the air vent fully opened and the chimney baffled for the entire session, manipulating the temperature by the amount of burning coals added at a time.
My strategy was to heat up to about 300 degrees and then let it coast downwards, hitting it with some fresh coals whenever it got down below 240 or so. I imagine the average temp hovered between 250 and 275 most of the time. I never spiked above 290 after that initial burn and never fell below 235 (I hit the bottom when I left the lid off the firebox for an extended period).
I had (the cheap) probes at the grill level opposite the chimney and in each shoulder. I have a spreadsheet with temperatures recorded every 15 minutes throughout the session. The session lasted for 10 hours.
In the middle of it all, we cranked out a batch of ice cream (Cookies and Cream, aka vanilla with crushed Oreo cookies) and I whipped up a batch of Lexington-style dip.
We ate purchased slaw. Don't judge.