Found a wire that already runs from the cabin that may not be required and could be reallocated to a more useful purpose. Powering boot popper in my case.

The trailer plug has a wire for 12v, pin 10, a Light Blue/Red wire. This connects to a plug under the driver's side dash.
Could be utilised to save running a run wire.

Of course, there are probably others. It's just one I've discovered.
Just a thought!