reheating for a large group

Smoke the butts the weekend ahead of time and just reheat them in the kitchen over. It will taste just as good. This is exactly what all of my customers do with the pork butts they purchase from me.

Or one of these
Your local walmart probably has them for 30 bucks, I will put my butts in and smoke so they are done the morning i want them, pull them and put in roaster, put a layer of foil down against the meat to keep the moisture in. If it does start to dry out, chicken broth and some apple juice will put some moisture back into it and not cover up the flavors.

I have take left overs from the freezer and put in the roaster with excellent results also.

Just keep your heat down to 160-200.