My enclosure is just under 5 feet tall, for a 7 month old jackson. Too big? Heck no, he loves chasing down worms and crickets I place on his vines. He stalks it like his own lil jungle, gaping if we are in his "bubble". They are animals and we must allow them to act as they naturally would in the wild, most often you will find on these forums people stress over them not eating, they are reptiles and have their own schedule. My guy will often go a day or so seemingly without eating, or so I think. So I free range a few crickets and sure enough they all disappear. Too big would be a whole room, and throwing in 5 crickets in hopes he can track em down.IMO mind you. They will develop a schedule and know when and where they can usually find food. My dude acts shy when I throw in the food but as soon as the latch closes...hes on em. Good luck.
My single panther chameleon free ranges in a small room approx 6ft x 4ft and 8 ft high. He goes everywhere in the room and knows where to go to get specific foods. Im sure you could get a bigger setup but maintaing your light levels might get tricky. Inside the room I have his original cage with a glass back and is open on the top and sides which is where I keep plants and mist. He knows this is where the water is and comes down when I turn it on. Crickets are allowed to wander but i hand feed the roaches, otherwise they would hide. There is a window in the room which i build an outdoor cage for when its sunny and he will wander into it and bask if its available.