Disclaimer: We must be careful with large lizards and sharp clause many times they will rip the material. Using are enclosure in a FREE ROAMING ROOM makes are enclosure the "Warm Zone" . Also I must say be very careful with the placement of hanging "heat domes". Always use a burn guard and thermostat.
This is an example of a "tortoise hatchling" best heat unit. Again, a frame supports a radiant heat panel. Set at 12" this shoots heat down onto ground which can easily be a hiding cave. The RHP would be perfect for any lizards or snakes. The top is also warm. Nice and warm with the hot zone on the opposite side. You can see in this case its clamp on heat units. With a trellis you can raise or lower them. 2nd option is to hang heat domes and raise and lower if needed. Higher up gives you a bigger spread of heat.
This example shows the use of a 4" full wood frame on the bottom. The wood should be primed and painted two coats. Urine and feces will stick to raw wood, looks count. Nice and clean looking area for the 4" substrate all while protecting the tents side. A 2nd example of clamp on heat lamps. Adjustable and excellent for some species. NOT SNAKES they will crawl on them. They may get burned.
This is to show how are frame works. The black hooks on the front must be lined up directly behind the " INFAMOUS VELCRO ". Velcro is crazy strong once you understand how to close it tightly. I pull up and start in the center push left and then push right. Are "excellent" assembly video even show the spacing of the bars. Follow those measurements. Then adjust the bars after tent cover is on. NOTE: white coroplast is included that can easily tape to the bars. Now the surface area is 4" wide to push Velcro against.
We all know that heat rises. So, 2 "hot air" exit vents will draw cold air in. Our tents have a 1" x 4" hot air exit vent with an adjustable cover. NOTE: on the back side in the middle of the "electrical port covers." Simply slice the mesh to pull the electrical inside. Cut a slot in the cover.