Trailer with rear steering axles

[SmallHaul]

Cables in an "X" pattern would probably work nice. The most important thing is the attachment points on both the back of the truck and the trailers steering have to be the same width so that both cables will be of equal length and tension regardless of how much you turn. One gives while the other one pulls...The cables would be permanently attached to the trailers steering and just have removable hooks on the back of the truck.

[SmallHaul]

One more thing that is important if you try cables..not only does the width have to be the same on both ends but, the pivot point has to be very close on both ends or you would get a lot of slack while turning. I use "pull pull" cables on my large scale airplanes for the rudder. It can be a pain to setup so maybe just play with some string and see if it is feasible.