Without saying go out and buy a vacuum sealer from you local store, try heavy plastic wrap after the butts have cooled and remove as much air as possible without wringing out the juices. Then zip lock bags. Important to keep as much freezer burn or ice crystal formation as possible from occurring while stored in the freezer. (A Food Saver is not industrial strength but they do a nice job). My butt leftovers are always pulled and vac'd or if serving the next day, just bagged. For reheating I use a large lidded pot with a little liquid (typically water) to gently re-heat within a moist environment and avoid drying it out. Then I sauce it once heated through. A large crock pot or a large Nesco type roaster will work well also. Just keep an eye on it while re-heating. I am not sure about reheating whole butts; never done it. I don't suppose it is any more difficult than 'cooking' a ready to serve shank ham in a covered roaster in the oven. But again, I have never done it so that is just a guess. Others should be around with some proven techniques that work well for them. And good luck!
