Our ladder extension will not fit or hang on the installed part of the ladder.
There are four clips in the bays for it above the trays. Doesn't work worth a darn.
It would be an ordeal to get it out if needed. I could hang it off the ladder but it would stick out a bit and cause problems and damage both of them. We have seen many that fit snug against the installed portion though. Looks like it would take some thought to protect them from banging together. If it will fit perhaps two long shackle bike locks with durable rubber, urethane preferred, hose over the shackles.