8 pound pork butt - too big for crockpot?
It all depends on the crockpot. Why not cut the butt in half and have two meals? Or, if you need that much meat, do it in the oven - 300F for 1 hour per pound. Use a close fitting casserole or other covered pan, add water, broth or BBQ sauce (or a mixutre thereof, until the liquid is half way up the side of the meat. This is a basic Braise.