re-wire trailer plug and your truck plug. so wires are swapped around. chance cops to pull over, due to turning on right blinker, but left blinker goes on, instead of brake lights, they get tail lights or some such.
see if one of your wires will keep trailer brakes on, if you re-wire the trailer plug and truck plug
granted makes for pain in rear if you let someone else use trailer, or use multi vehicles to deal with trailer.
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toss a lock on the jack, so you can not raise/lower without taking off lock. (jack welded on to frame of course) and keep end of trailer high up off ground. so they can not just go over and lift end of trailer on to truck but are actually required to let jack down a few inches to get it attached to a truck.
it been some time since i have seen them. a "ball lock" when you disconnect from vehicle. a ball that slips in, and then a U that drops down from above. like a muffler clamp.
i have never been to crazy about getting on hands and knees to put a chain through tires, or dealing with a tire locker. more than likely wet/muddy / dew on ground. when i need to deal with it.