For my bottom cowl ((L-IVP) I use 1/16 inch thick  "fiberfrax" from ACS which is said to be good up to 970F.  It goes on with a special High temperature glue.  I also use a 1 inch wide high temp foil backed adhesive tape from McMaster Carr to line the edges.   Relatively easy to work with and inepensive.

Regards, Bill Hogarty