I used a Camelbak military spec backpack. I took out the water bladder. I would load it with the track sack (with chainrings and cogs and small parts), then tools, clothes, shoes, numbers, pins, pens, snacks, water bottles, etc... would go into the rest of the bag. I would clip 1 or 2 helmets to the outside of the bag using D-rings. Then I'd hike it on to my shoulders and my hands would be free to walk/carry the bike.
So, I'd have bag on back, race wheels strapped across my chest using a long strap, then bike in hand walking it (or on shoulder if in parking lot). The other hand would be free...for signing autographs
...lol j/k...I was actually signing checks to pay guys to make me look good in races