GottaQ...
I get my butts from a hog farmer. Usually they are fresh off the pig, BUT, when she is out...she has a pretty small operation....then she will order it from a meat wholesaler. The cryovacs are always around 16-19 pounds.
You are correct about not cooking the entire time....and I think there may be some confusion on this point....Once the meat hits 200�, I will foil and then place back in the smoker and close all the vents. This effectively stops the cooking, BUT is still warm enough to hold for several hours. The WSM is pretty efficient in this manner and I am sure some additional cooking is done, but for the most part, it is used to hold the meat.
I have also never had a problem with a nice thick bark. Though the foiling will soiften it up a bit, it is still there and I mix it in with the inside meat.
I guess the whole point of this experiment is...you cannot overcook a pork butt!! To a certain point! So, for me, it makes sense to have the best of all worlds.....sleep and fresh butt!!
Popajack...
Here is the injection I have used in the past. Be sure to powderize any rub that you use..this will facilitate dissolving. I use my burr grinder or a mortar and pestle will work as well. If you have a rub that won't dissolve, be prepared to have "streaks" of solid rub throughout the meat.
Pork Injection Marinade
4 cups Apple juice or cider
1 cup Cider vinegar
1 cup Water
1/2 cup Worcestershire sauce
2 tablespoons Pork rub
1/2 cup Corn syrup
PREPARATION:
Inject into pork butts at the rate of 1 ounce per pound of meat.
Use as a drizzle on ribs before foiling.