That would probably work if you got good contact between the flat surfaces. The only way to know is to try it. Downside is if it doesn't work you're kinda screwed. The camp chef flame tamer plates are relatively inexpensive though at around 12 bucks a piece. They weren't available when I needed mine so I had a metal shop make them for about double that or a little more even. But I needed them so I just got them.
