I'd like to do a about a 6 1/2 lb butt this week on my Small. Is this doable? I was planning to fill the fire box with lump. Control of temp has been easy since I jacked up the lump grate about 1/4" with 3 Stainless bolts. Lots of air. Will a full box give me enough for an 10-11 hr. burn? Thanks guys!