I believe the key to having a small chameleon in a big cage is to fill the space with climbing opportunities. Do not have large expanses of empty space. Fill the top area with branches to within an inch and 1/2 from the top screen to prevent constant climbing on the screen. Using natural branches from your neighborhood should make this much easier than trying to simulate branches with commercially available fake vines. If you are worried about spiders or other tiny insects you can bake the branches in the oven for 10 minutes at 350F. I use plastic zipties to tie the branches together. The picture is an example of what I do for juvenile panther enclosures.