I just love your project! I have fallen very fond of swiss cheese plants. They have large leaves for shade and sturdy stalks that rarely break. They also grow well and are easy to care for. I have had a leaf burn by being directly under the basking light but direct sun may be ok. Since you have the space, you might want to consider a rubber tree plant. I have one potted outside and it grows great and my veiled loves climbing in it as it can take the weight. As a matter of fact, most of my branches in in my 2x2x4 are from a rubber tree. you can find ones that are bent and tapered and great for creating a jungle gym. Keep us posted with pics.