Honestly, if there was a way to attach them together (say, a clip), I'd be fine with a brick. Make the clip provide a small gap and airflow should be good enoug

Honestly, if there was a way to attach them together (say, a clip), I'd be fine with a brick. Make the clip provide a small gap and airflow should be good enough to prevent thermal issues. If I do run into problems, I can always separate them...