In its current form, I dont think the radiant heat , will matter much. I doubt this car will run long distances on the street, and a burn out -staging and pass should take something like 45 sec to a few minutes of run time at the track. The aluminum rods will limit the cruising some what. If you see most of the Pro cars, they use nothing to insulate the IC.
I was adviced to insulate the unit with a special thin plastic insulator used on refrigeration units. I have the link at work. Its thin... almost like Dynamat.