Bar Stool under bench mounts

We have a couple of robot vacuum cleaners, so my wife always puts the bar stools up on the kitchen bench to allow them to clean under there.
I first tried installing some brackets under the bench to hang the stools slightly off the floor. However, you hit them with you knees when sitting at the bench. So In decided to make the brackets swing up out of the way when not in use. These work well.

To install them, essentially you have to mount the brackets in the retracted position (as shown in the last photo). First take one bracket and install the link in place (refer to the pictures). Install the mount into the bracket and screw it to the underside of the bench, ensuring that the bracket is pushed up against the back wall of the bench which helps to stop the link from working its way out. Then take the bracket you just installed and swing it up against the bench underside. Attach the other bracket to the other end of the link in the retracted position also, then (ensuring both brack