For areas where you need to protect "stuff", add THIN aluminum heat shields, and make them as large as possible (surface area). Make areas of the heat shield reach into areas that are NOT direct hot. By using very thin aluminum, the heat transfer (in terms of distance/time) will be very quick (into areas that are cooler.) You can move the heat any direction you want, regardless of airflow, and even sink it into components that can accept some extra heat for a while.
You will be amazed how much heat you can "de-concentrate" (there's a word for ya'). If you chicken out and use thicker aluminum, all bets are off..... it's not about resisting the heat, it's about capturing it, spreading it out and moving it FAST.
Look under any modern car, how the heat from multiple catalytic converters is managed, with 1800 degree parts... 1 inch from your ankle! Also, the texturing you see is another aid to rapidly balancing the heat. Crawl under the junkers at the pick-a-part and buy all the interesting shapes and lengths you can.....I've got them under my street rod and there is NO problem with heat coming through my floor. I have not added any "insulation" (which often turns into a a heat sink, in my opinion).
Regards, JimL