If you have boneless pork shoulders from costco, you probably have 2 boneless butts per package that weight in the 6 to 8 lb range. So they are already divided so to speak. I'd tie them up, and cook till they probe tender. Might be a good idea to start the cook the previous night, so they'll be done 3 to 6 hours before serving time. Rest in a cooler/cambro till time to pull and serve.
250-275 would be a great temp range. Foiling? I never do it till rest time, but always have a very clean fire burning and use low sugar rubs, so I don't have to worry much about the bark getting too dark.
Apple and hickory is a great combo. If you ever get access to pecan, I suggest you try that along with any fruitwood. My fav wood combo for anything pork is half pecan, quarter apple, and quarter cherry. Hickory and pecan are very similar, but to me pecan has a sweeter aroma coming off the pit (makes the whole neighborhood smell wonderful), and it is hard to oversmoke with it.
Modded Brinkmann Gourmet. Basic UDS. Rescued 22.5" OTS. SJS Mini-WSM. Stubbs. B&B Oak Lump.
Cannondale 2009 F8 (for burning off all the great BBQ)