Sorry- meant to get back to you sooner. I've not had the opportunity to swing by one for a better picture...
ATTACHED are two pictures that I was able to dig up.
We've gone with long 2x6" boards with bicycle hooks every six to eight inches apart and just alternate the bicycles hanging with handlebars up, then down.
The hooks within the container serve as our point at which to secure the 2x6" with carabiners and chain. We've also been successful with strong tie-downs from the hooks built within the container to the hooks at the floor of the container directly below (or should be directly below)
Our most secure way has been to use both the carabiner, chain, "s"hook to an 'eye' hook AND use a tie-down for stabilization of the entire 2x6"
- Using both is a way to ensure there's extra strength should something fail. Use the long strap of the tie-down to wrap around the 2x6" once or twice as this will also help keep the 2x6" from coming out away from the wall of the container, side to side, etc.
This is not the best, but it's relatively very inexpensive, easy to set up, and can be done by 2 people in an afternoon. Key is using the strength of the hooks already built within the container.
I would also recommend that you do not drill holes in the container. It's tougher to do and keeping it in as best of shape as you can with it in mind as an 'asset' for whatever the future might hold (selling it off when you no longer need it, giving it away, etc.) just keeping it sound in that regard without permanently damaging it has been our approach.
Hope this is helpful, keep up the great work!, and let me know if I can be of further help to you.