Check this out...I found this and ordered some just to see how it might fit. Ceramic Fiber Paper
https://sealwiz.com/product/ceramic-fiber-paper/?attribute_pa_thickness=250&attribute_pa_width=48&attribute_pa_order-by=short-roll
CeraTex® 3170 Ceramic Fiber Paper is an alumino-silicate ceramic...
I just purchased an RT-1070 and realized I need something to insulate the grill from my combustible cabinet made from wood and hardieboard. I called RT and they said they don't carry anything like this and basically, good luck finding one. I have already had the structure built with the grill...