^ with a bungee tie.
I would clip the bungee onto the original place for it. If the horse moves around a lil its fine.
-- I wouldnt worry about the butt bar or chain-- Not needed in that situation. Id only really be concerned if it were still in 'straight load' mode. The way your horse will be tied she will be slanted. Removing the divider basically turns your straight load into a slant.