gijoecam wrote:
Second, I have yet to see a configuration that would allow the breakaway cable to be pulled when the coupler separates from the ball but the chains are still attached. It would require some very specific-length cables and attachment points such that the cable is pulled if the ball drops more than a couple of inches, and that assembly would still need to be able to articulate as the rig makes turns and traverses hills and valleys. That setup only exist in theory as best I can tell...
If the breakaway cable is routed directly above the coupler (e.g. through the coupler padlock), it can be tight without causing issues while turning. Not that I have an opinion about whether it should pull first or not. :)