what if you took this idea inside with a slightly different design and had some form of "locking" from the inside that can be released by smoke detector from inside plus a manual saftey release even a child could release.
Cut legs A & rails B, C to size. Cut hand hole & mortises for hinges in back rail. Cut half lap joints in legs & rails. Lay assembly on bench & clamp swing-leg assemblies on top in open position. Make sure top edges & outside faces of swing-leg rails