All good ideas! Ceramic coated headers make an incredible difference in keeping the heat inside the headers.I think one the biggest things I can do to help is to control the main source of heat: the headers.
Next step would be some sort of heat barrier/insulation behind the dash and on the floor.
Another thing I plan to do next is tinting the windows 20% with a good thermo blocker.
When you have the heat control all the way to the left (shut off), do you still feel some warm air coming out of the vents? If so, put a water shut-off valve on your heater hose.
Even in a white car with a white interior and working A/C, I still stick to the seats in the 95 plus degree and 95% plus humidity we have here.
All good ideas! Ceramic coated headers make an incredible difference in keeping the heat inside the headers.
I used Dynamat brand but any of that type of insulation works wonders on keeping the heat out of the interior. If you have a console, make sure you seal in that area as well.
That being said, 85 degrees, probably humid, no ac......you are probably still going to be pretty damp when you get out of that car after 30 minutes. ;)