Insolated Risers

A third option would be to use large metal washers as the chill plates, and puting a small riser up threw the center hole. The risers would only help fill the shrinking metal for a short period of time though, and I don't know if it would be worth the effort. It would however be an excellent place to mount a vent...

PS. Nothing about these drawings is to scale. Just my doodles to get a better idea of what I'm doing.