We had shedding issues with our ball python due to low humidity so we took a large, rectangular plastic container, turned it upside down and cut a hole in the side large enough for the snake to slither inside. Then we placed a damp towel inside and set the container over the area of the heating pad so she had a nice warm, humid area to go to. Worked like a charm!
So we're trying the same with the iguana. I got a large rectangular plastic box, cut out most of one side, set it upside down, put some damp paper towels on the bottom, set her favorite flat rock on the paper towels, and set that over the heating pad area. First night she was inside it, sleeping and she loves it. Her shedding is already looking better!