So my new idea is to work with him on a long line (my BO has a 22 ft line that I can borrow, its got weight to it which is nice) still in the round pen, and since he works well leading and on a lead line, just do the CA sort of method and back him up every time he gets possessive of it. My question is, once he starts behaving, should I back off the food, or stand there till he's done eating? And then do I leave it at that, work on other ground manners before turning him out (He's on night turn out, so he eats and then goes out)? OR, should I lunge him first for like 10 minutes to get him paying attention, then work on the food aggression, and then turn him out?