Since the horses are not very fast nor smart (Frost tends to charge up two flights of stairs to attack mages on his own) and the companions are not very bright and keep Hurting more then helping I'd like to pre pose the stables sell Sadler bags or pack horses.
A horse or bag for the horse that enables them to carry a ton of loot for you and the all important command of STAY, also I wouldn't mind a "whistle" command like RDR for when I come out a different spot of the cave then when I went in.