I'm convinced that breakaway switches are probably used wrong by at least 90% of the rigs on the road - and that's because none of the dealers or manufacturers take them seriously.
Almost all the TT's I see nowdays have the cable clipped to the loops designed for the breakaway chains. The rest have them someplace even worse - hooked over the hitch ball before dropping the coupler on it.
As someone who's had personal experience with a hitch breaking loose from a TV I can tell you neither of those are optimal. My hitch was an aftermarket - welded on by someone with insufficient experience in welding. It broke almost completely free before we managed to stop the rig.
But in today's world - almost all hitches are factory installed and bolted on. The probability of the entire hitch breaking free is probably statistically very very small. The biggest risk is that the hitch ball nut get loose and you don't notice (has also happened to me), or you forget to put the latch down on the hitch ball and even with the Weigh Distributing arms, the hitch bounces off the ball which I think would be very hard.
Not sure if the breakaway cable should be shorter than the safety chains - I've never actually seen one that was - all of mine over the years have been longer. It does seem to make sense but . . .
So it's probably fine to clip the cable to the same place you clip the safety chains/cables. However, I'm also a big fan of the coiled cables.
I wonder if any crash testing agency or RV manufacturer has actually tested what happens when a trailer breaks free at a high speed and stays connected by chains - I certainly hope so . . .
But a quick Google search turned up this rather radical web site: Dangerous Trailers - Saving Lives
Be warned the navigation is horrible.
If you dig around enough they are mainly advocating for federal standards for hitch components, state laws in all states on safety chains and breakaway cables and state inspections.