The idea is for the cable to be a last resort. Your chains will catch the tongue of the trailer (they are crossed beneath it) if the hitch breaks. I have no doubt that if the trailer falls onto the chain, I will be very aware of it. If the chains then break, the cable is your last fail safe, and the trailers breaks will activate keeping it from rolling on down the road.
I drilled a hole to the left of the hitch through a part of the truck frame (not the hitch frame) and stuck a snap clip through it. Now it is a simple matter to hook and unhook the safety cable, and I don't have to lean over any more than to hook the chains when I am down there.
Craig and Carol
1997 34' Excella 1000
1970 27' Overlander, International
2009 Ford F150 5.4L
ProPride hitch with 1400# bars
Past President Southeastern Camping Unit (12)