Hmm. Definitely an interesting idea. Downside: manage to e.g. swap a 12V and 48V line and while an 48V component shouldn't be damaged by 12V, a 12V component which does not have a voltage regulator in front will get fried. It's nasty enough with a truck with dual voltage and trailers - a 24V trailer will at least be recognizable as the lights will simply have a dimmer light but a 12V trailer on a 24V truck means hours of swapping every goddamn tiny light bulb. Add a 3rd voltage into the mess and the potential for chaos multiplies...