I can understand your position on the breakaway cable, mowermech! I can imagine that situation, but the idea of a vehicle attached to the motorhome only by the safety cables would be wild too.
Let's say you are moving along at 70, and the towbar gives way but is still attached by the safety cables. Now, you have 1.5 - 3 tons of vehicle flailing around back there, and how do you stop this parade? If the toad is in fully braked mode, at least it won't be crashing into the back of the tow vehicle as you attempt to come to a stop.
There's going to be a lot of damage, either way.
According to my Demco Stay-in-Play instructions:
Step 13: The Breakaway Cable
Clip the breakaway cable to the hitch-receiver tow-cable holes on the coach and clip the lanyard to the loop on the breakaway plug. The length of the cable should be long enough that it will not pull out on the tightest possible turns made in either direction. Also route the cable so that it will not get caught on the tow bar. It should be short enough that it will pull out before the towed reaches the end of the safety cables.
2016 Forest River Sunseeker 2250SLEC Chevrolet 6.0L