I use Reflectix, you can pick up a roll at most large hardware stores. Relatively cheap, can be cut to shape, can be used for other things, easy to keep clean.
https://www.homedepot.ca/en/home/p.b...000407996.html
Cut it to fit and then put duct tape around the edges to make a good seal. In theory the red lamp heats the air on warm hide side, and the warmed air vents through the hole on other side, providing a small, constant air flow.
Still need to mist the enclosure every day but that's not a big deal. Usually I'll mist in the morning, and/or in the evening when I re-fill the water bowl.