If the butcher has totally removed the outer layer of fat, I would cover the meat with thick slices of bacon, or buy some fatback (pork fat) and cover the outer layer of the meat. The internal fat in the shoulder will keep it well moistened; you just have to protect the outside. Putting the shoulder in a foil pan may protect the bottom of it and not the top. And if you cover the pan with foil, then no smoke will reach the shoulder. Were you planning on grilling it or smoking it? Pork shoulder is best smoked on low temp for a long time (low&slow).
If you want to pull it, then make sure that the internal temp reaches 195 degrees.
I hope this helps.