Hi "Doc",
Your post reminded me of some guys I knew that had small boxes they left in their car. They had a small box called "The Repair Box" that held CA, 5-minute epoxy and stuff to mix it with and trim monokote and scissors for patches and etc. They also had another slightly larger box called the "Backup Box". Their rule of thumb was, "If I use it regularly on the circle, then it goes in the flight box, if I might need it but not regularly then it goes in the "backup box" and stays in the car". "Don't lug around anymore than needed". They put in extra sets of lines, extra handles, extra props, tools they might need but not regularly and etc. Sounded like a good idea to me.
"G-man", perhaps you could incorporate some of "Docs" ideas. If you went with a roll around "toter design", you could "modulerize" the design by have boxes of the same size , that are tailored for different type of aircraft, all fit in the same space on the tote. You just grab the module you need pop it in the tote and roll away.
G-man I think before you design any box it might be a good idea to get all of your "flight box stuff" and lay it out in front of you and then consider your list of "new stuff". Your objective is to figure out how it would all fit together, and how you would use it all, and maybe, that some of it should go into a "Back-up" box because you don't use it regularly and you really need the space for something else. What I am trying to say is to start out by evaluating what is going into the box before you design the box.
I am sure you have thought of that before, but you have been given a lot of flight box ideas, so I just thought this approach might help you sort it all out.
Best wishes,
Pat Robinson