Yes, that's exactly all I had in mind - to simply cover the carpet. Needs to be something fairly rigid so that the feet of the computer don't just sink it in to the carpet though, eg: a thin sheet of plastic wouldn't be much good because the computer would sink in to the carpet anyway and the carpet would mold itself around the feet and block air access.
That's why I thought of cheap chopping boards.
That's why I thought of cheap chopping boards.