Park it in the shade?
I used the Peel & Seal on the underside of the roof and on the underside of the cowl forward of the windshield. Does it keep the heat out? I don't know. I don't have an infrared thermometer to test it. The headliner sure does help keeping the heat off of my bald head.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission