I agree that in retrospect there had to be signs, In this case the sign was the lowering of the front of the trailer recognizable by the visual position of the rock shield latches against the Honda's rear window's heating elements. I use these to check that the trailer is leaning to one side or the other and not looking to see if it's lower, obviously a mistake.
I agree it's hard to catch every scenario however relocation would catch the trailer and A frame separating. With the stiffening of our frame I doubt that failure could now occur.
I seriously doubt the axle
off though certainly a wheel could go and would quickly announce itself. We have added pressure/temperature sensors to our trailer tires
to help us see trailer wheel and tire problems. An increase in temperature on a trailer tire compared to the other can serve as a warning. We have already seen this on one of the Honda's tires
where the temperature increased quickly on one of the rear tires
In that case we stopped put it in reverse.
Now retired and virtually a full time trailer person, I have a lot of time to think about the rig. You know, free from the work-a-day world.