The lower leg and butt are no different than your upper arm and shoulder. There is the leg bone in the socket of the shoulder blade. Cut the muscle and tendons at the joint and you have what will be a ~13 lb Butt and an 11 or so lb Shoulder (lower leg). If you plan to cook it whole, it will take just a little longer than if it was separated, but in this case the over all dimensions are more important than the weight. The narrow Hock end will get done sooner leavng the skin on there will slow it down, but over all a whole shoulder is fairly uniform. Same as a Loin, a 12" 5lb piece will cook about the same time a 24" 10lb Loin because they are a fairly uniform height and width over the whole length..
First off, everyone has a Temp that they are used to maintaining in their smoker and that is the temp they smoke their Pork at...A Party is NO TIME to be messing around trying to smoke at some other guys temp! If you are capable and comfortable at maintaining 225 in your Smoker use that temp. It is rare that a large Butt or whole shoulder will be done at 225 in under 2 hours per pound. If you look at this thing as a big 12lb Butt at 2 hours/lb, then your 24 hour cook time with adding a 2 hour CYA/Rest in a cooler will get you done in time if not early.
There are variables, some companies " enhance " there Pork by injecting a solution the keep it moist and charge $3 a pound for the added water, but the amount of Pan/Foil Juices will vary greatly and are mostly rendered Fat. There is HUGE flavor in the de-fatted Dripping and should never been thrown out. If you need all of the juices to moisten the meat, then use it. If not the leftover drippings will be needed in the leftovers as there will be evaporation keeping the meat hot throughout the event and meat absorbs juices as they cool. Extra Drippings add Flavor to anything you wish to add them to. Baked Beans are always the most frequent use for Pork Drippings but it will add a little bit of pork and smokey goodness to anything you add it to. BBQ Sauce, Collard Greens, Vegetables, Gravies, Soups, especially Ham and Bean or Pea Soup, Carnitas or other Taco Fillings, the list is limitless. Pour extra drippings in Ice Cube Trays and freeze them. Once frozen bag them and add a frozen cube to anything that can use the flavor...JJ
@Timberjet...The 4 hours to 140°F only applies to Injected, Ground or meat that has had the surface broken, like guys that poke holes and Garlic Cloves into the meat or Boned-Rolled and Tied meat. Bacteria has no ability to get in meat and is only on the surface. The issue with breaking the surface is you may push some of that bacteria in where given enough time can make Toxins that make you sick. The Bacteria itself is killed at 140°F...