If it were me, I'd consider emulating the folding-stock design used in the G-36, and adapt it to use in the wood stock (i.e., cut the stock, embed a hinge, add a simple securing latch). It would end up shorter for packing in a case, and would be less...obvious.
Another way might be to cut the stock just ahead of the pistol grip, inset a nut into the front part of the cut, and run a long through-bolt from inside the butt plate. Maybe even make the butt plate swivel for easy access? Make the hole behind the butt plate big enough at the end to use a butterfly end, so no tools are needed? There are lots of ways, I suspect.



























