Erm...
If you want to make an articulated 1 wheeled trailer (no castor wheel) your 'tow hitch should be a universal cross as found in driveshafts on rear wheel drive cars.
Now you have the left n right and the up n down for the bumps etc, but to fall over the trailer has to 'twist' the car into falling over...
ie: You need 1 (one) of these crosses and the splined bit:
https://www.google.com/search?client...n5BAqSb2Q,st:0
See that splined bit: that splined pipe or the shaft bit it fits around is solidly mounted straight back behind center of the car.
Drill a hole through that for a pin and you have your quick disconnect.
The cross stays with the trailer.
NB that your main forces are now in the direction in which the splined bit used to work to negate such forces..!
Choose crosses with thickness in that plane or/and go big!
NB that this works for motorbikes and bicycles etc too...
('big!' : not so much.
)