Can you tell us what the temperatures and humidity are? Those are going to be big factors in the suitability of your kiddie pool enclosure. Most open top set ups aren't suitable because they don't hold heat or humidity, but if the room he's in is warm and humid it could work.
I have a really similar enclosure for my Red Foot right now, through I'm in the process of building her a table . I find that it's actually very easy to maintain suitable conditions, as long as I'm always checking humidity that is!
I keep my tortoise in my living room/dining room where I maintain pretty warm temps for myself anyway. My pool enclosure is also elevated up on its own table. I will always recomend that, so kitties and puppies will stay out. I will always advocate the kiddie pool enclosure, as long as you do enough research to maintain correct conditions!