As long as a chameleon has enough plants, vines, shelves, etc. they rarely wander. They may wander if hungry though. The few times my veiled had wandered off he could predictably be found in a closet perched on clothes hangers.. Maybe he liked being somewhere cool and dark sometimes?
I've always free ranged all of my guys. They do get down and wonder around so I have corals around the bottom of baby trees or the trees of small chameleons that might could get lost in my house. The most important thing about FR is to have a safe FR area....like a chameleon proof room where you can close the door. You also have to be very careful when you open the door because they could be right behind it. www.chameleonforums.com/photos-some-free-ranges-137228/
My only concern is that they would get stepped on or sat on. It happens all the time with clipped parrots who end up walking places rather than flying. I liked Jann's corals--that would keep them safe.