That's a great idea, Paperdolls, cheap and it just makes sense.
I use my laptop mostly at the dining room table because I have such a lovely view of outdoors and it's handy. I put a cotton quilted place mat underneath it, more to protect the table from heat than anything. But I don't overheat ever and my table stays like new as well.
Good luck, I'm sure there are many inexpensive ways to let the air flow.
Hugs