Paint the container with shades of rust, browns and tans and then either do the salt trick where you sprinkle salt on the surface to "mask" tiny spots or you can paint tiny specks of rubber cement instead. Ater that dries, paint the container the color you want it to be. When dry, rub of the salt or rubber cement and you'll have lots of "paint chipped areas" Then you can further weather the container using very thinned out gray and tan paint lightly misted on. You can also use a flat aluminum or silver and very lightly dry brush areas where the container would make contact with other things and around the rear doors, etc.