I second the idea of reheating in a plastic pouch. I store my pulled pork in vacuum bags. I weigh them before I seal them, and put 10 ounces in each. This seems to be just the right amount for the two of us. I freeze this. Then, when we want a pulled pork dinner, I just throw the bag in some hot, but not boiling water. Sous vide would certainly work, but is definitely overkill, since exact temperature control is not needed. After all, you cooked the pork to 200 degrees, so it isn't going to be a problem if you get it a little too hot.
I have a nifty portable induction cooktop which has a temperature control which senses the heat in the bottom of the pan and moderates the power to maintain a given temperature. It gets you to +- 20 degrees. This is not precise enough for many things, but is plenty good enough for reheating. I set it to 175, fill a saucepan with water, and then put the pouch in the hot water. While it is heating I make coleslaw, thaw the buns, set the table, and by the time I've got everything set up, the pork is ready.