You’re way overthinking this.
Ditch the loopkey entirely. Have a male
XT90 come out of the enclosure on short 12AWG wires, which runs the ESC(s). Have a female XT90S plug in the side of the enclosure which is the main battery. Plug that together to turn it on. OR, strap another battery to it, and plug the ESC into the strapped on battery’s female XT90S.