Table Question

I am building out an outdoor kitchen using steel studs and cement board (BBQ Coach system), so there aren't really any combustible components (i.e. no wood). 

At my own fault, I put together the BBQ coach egg module to be at a 12 inch height from the shelf to the top, rather than 15 to 17 inches for the large Egg. I can make some modifications to get it to maybe 13.5 to 14 inches, but I already have a drawer installed underneath, so can't get much further. Anyone see any issues with this shelf height besides the Egg sitting a bit higher than optimal?

Also, I know most folks recommend the Nest and then even potentially firebricks or pavers underneath that. For my scenario, since there are no combustible components and I need to raise the GBE enough to have a small airgap, but don't want to raise it too much, I was thinking of putting a stainless steel sheet (heavy gauge) over the cement board and then using the ceramic feet instead of the Nest. What are your thoughts on this? Neither the cement board or the stainless steel are combustible and there would be an approximate 3/4" airgap.