Detachable towbar

[Lightspeed]

Some of the removable tow hooks are held in place by slide pins, like the ones on the Dixon Bates units Dev mentioned.

These pins are awkward to move when unloaded, once they have the weight of a trailer bearing down on them they are pretty much locked in place by design.

A cable arrangement to pull the pins in their loaded state seems implausible.

If you are intent on this craziness the only ways I can think to move the pins while on the hoof I can think of would be to rig up some sort of mechanical press: Electric motor driving a screw, Hydraulic press driven by a pump, Pneumatic press driven by a pump.

It'd be interesting trying to explain away an installation like this to plod, MOT station, or even your mechanic...