I dont know what a "Toyota Hundy" is or its market area.
Anyway, Typical of that era Toyota 12v aux receptacle is, its controlled by a relay in the underhood fusebox. This relay is switched on/off by the ign. key. Its contacts take 12v from the unswitched buss (thru a fuse of course)
One can unplug the relay & fit a jumper in place of the relay contacts.
Its easy to do & easy to restore back to normal.
I did a variation of this on my Hilux. Left that relay alone & I installed a 18Ah AGM battery connected to the aux. receptacle circuit.
When the truck is "on" the aux circuit is live and also charges the aux battery. When the truck is "off", the aux circuit is still live but being powered from the aux battery.