[rawfuls]

I like Pinkpanda's idea, hardcased with bullet internals.

I'll be honest, I didn't read much of the thread... so not sure if you threw it out already, but..

You would mount the bullet connections on the chassis, and pull straight up if you wanted the battery out, push down to mount.
To lock, just a velcro strap, or a twisty metal mount (imagine a C, the cutout on the bottom, held in by a screw somewhat tight but still moveable, like a pivot, then pivot the clamp over lipo).