If your referring to the set-up on post 1945, a few feet maybe.
Not with a ball mount for the small trailer, one little bump will end up with slight turn the trailer will start turning out of control until you stop.
You cannot control the trailer to just turn slightly, with a ball mount hitch.
Now maybe if your backing down hill a little the force might keep it straight for a few more feet.
Now if the guy prefers to believe you he can continue trying with failures along the way.
What everyone does with set of doubles as pictured is drops the rear trailer in in a convenient area, sets up his/hers trailer then goes back a hook up his little trailer and take it to camp.
Even with the big rigs set of doubles, if your on a perfectly flat road you might be able to back up 20'-30' max.
The hitch set up is a little more complexed and takes a little more effort for the trailer to stay straight.
Your post does not even count for what us rv'ers use for hitches on doubles.
Mr 77cruiser that has a big difference hitch set-up than a simple ball mount and/or even the hay/grain wagons.
Pay closer attention to what your posting for comparisons, a few will fall for this.