You may want to consider a Garolite material similar to this instead of a metal product. It's basically a high strength epoxy material that is reinforced with fiberglass mat.
http://www.jjorly.com/g10_fr4_sheets_fabricator.htm
Don at Hermco told me about this but it's pretty expensive. While browsing the McMaster Carr catalog for work one day I found an alternate product which offers similar characteristics although it's not as strong but a lot cheaper. I'm talking 10,000 psi versus something like 40,000 psi for the garolite. I'll be using it for the backing in my deck.