I'm pretty sure this has been talked about a lot in the electronics section. Here are a couple threads that seems pretty detailed:

https://www.jk-forum.com/forums/jk-electrical-lighting-sound-systems-13/wiring-tail-lights-towing-2000/

https://www.jk-forum.com/forums/jk-electrical-lighting-sound-systems-13/trailer-wiring-harness-954/

Hope that helps!

 

Sounds like you also need some slack in your wires. When I tow a trailer there is enough extra wire to angle anywhere, sort of like the safety chains.

 

How big is the trailer? Just watch the weight, these thing arent meant for heavy trailers. The 4 pins are standard and yes as stated above you need a controller for electric brakes,, If the trailer is big enough to really need the brakes make sure it isnt too big for the jk,,,
Steve

 

ditto - you can get an adapter to 7-pin but it won't operate the brakes. Search for other threads about adding the 7-pin - there are a few addressing the same question.