Coming from an industrial insulator amonst other trades. Best and cheapest insulation wood bee 2 inches of what they call mineral wool. What we used on power houses good to up to 1,200 degrees F. very inexspensive. Not knowing your heat load you can get what ever thickness you need and multi layer it if need be. This can be held in place with anchor pins and washers glued in place. Finished with alumium .016 metal flat stock. Let the pointed end of the anchor pins protrude the insulation into and thru the metal then use your rounded 1 inch rounded washers to hold the insulation and metal together. BOB knows what I am talkin about. Very cheap, looks good, shiny, can take abuse, and best hot insulation you can purchase. Then there is Armacell 2,000. Rubber, glued in place and painted for finish. Glue is $50 a pint, rubber is $20 sf. Works, easy to manuver with, paint any color, but will not take a beating. Will neeed to finish with .016 sheet metal. Metal can be cut easly but to go any thinner .010 is like paper and want take a beating. Depends operating tempt. Send me a PM if want more info. Wish I could be hands on for ya but a bit difficult from here. Easy operation if I were there. Find a local insulator to help. Want cost that much if he knows what he is doing. gettem Bob.
Hickster