It took years to come up with something that met the requirements on paper.  The leading idea eventually became clamp on legs with a bathtub for the battery.  The 1st printout instantly revealed the problems.  The clamps instantly came loose with any tugging, although the 8 were redundant enough to keep it together.  It was not possible to undo the clamps near the switch without a tool.  The battery didn't fit through the front & back.  It had to go in the sides.  The clamps had to bend too much to get in.  They might require a .4 nozzle to be sharp enough to not need such a depth.  They could also be longer.

The clamps should be built into the bathtubs & grab in front & behind the legs.  They would be more assertive & wouldn't need to be separate parts.  The 1st prototype might still work in a pinch.

If the diagonal legs were straight or curved, the battery could go through the front & back.

Storage was manely impacted by the clamps sticking up.  Z seam placement is killing the legs.

If the top bathtub was slightly shorter, it could be stored inside the bottom bathtub.  A tweak to the rear legs could make the top shorter.

The holes in the sides made it hard to get the clamps on.  The area where the clamps slide has to be flat & needs some kind of guide.  It can be thinner.

The quest began for a low voltage cutoff.  They all currently require building a discrete circuit.  There's no single chip solution for 10V or 6.7V.  The MCP120 was a TO-92 cutoff for 5V only.  The search term is supervisor.  It's going to be easier to have an unregulated pilot light show the charge level, since the mane light is constant brightness.