They only fight when food is involved? How about just teaching them their places and not to bother the others when eating
. Same goes for toys. Our guys sit and wait for their bowls and eat when I say "ok." When done, they either sit back in their places or walk out of the kitchen. They've even transferred what we taught them to the outdoors. They can all have a chunk of meat/bone and they go to their own places, never bothering one another, and I don't even need to be with them to supervise.
Same sex packs 'normally' don't cause problems, it's when you add an opposite sex where you'll really see dogs vying for top position. Good training and learning to read their body language goes a long way to interrupt and prevent any serious fights.