Trailer wiring length?

So tomorrow the new wiring and lights go on my camping trailer build. Not having done this before, I have no idea how much further forward of the ball the plug should be.

FWIW, the car-side wiring kit leaves the mating plug inside the car. I'm fine with this. I feel the minor odds of ruining the hatch seal far outweighs the potential damage of leaving the plug outside the tow car.

So, if any of you have a factory-wired trailer, how much further forward of the ball should the trailer-side plug extend?

I don't have it handy to measure, but the plug on the factory harness on my open trailer, stretched out, is probably 12-18 inches in front of the ball mount. Works out pretty well with the factory 7-pin connector on my Chevy truck, which is located about about 8-10 inches left of the hitch receiver.

If you've got the tow vehicle and trailer handy, hook them to each other and run the wires til you have just the right amount of slack.

If you can afford it, I've taken to wiring the trailer up to a receptacle on the tongue and then using a short jumper cable. Keeps me from clipping the end off with the mower when I mow around the trailer and I can keep the cords for each combination of vehicle and trailer inside something and out of the weather.

If the plug is off to one side, you may need more when turning the opposite way, you an always use a bungie type arrangement to hold the harness off the ground.

Do not cut yourself short.

Whatever you think, leave it a bit longer. I've got the leads on my trailers zip tied in a small loop to take up slack. That way if I ever tow with a different vehicle that needs more slack I can break the zip tie.