What I said before. With now 10 seasons, thousands of miles each season, I've never had a heat issue from the footboxes. That's with full insulation on the inside and carpet. I happen to mostly use Lizard Skin, but that's just one choice. There are many others. There's basically ambient air through the transmission tunnel, so not a huge concern there. I use heat and sound on the entire cockpit, plus typically the trunk. But the trunk is optional. Some don't bother. Gives max heat protection everywhere plus an overall solid feel and sound. Not sure what your friends are doing. But my experience (and many others...) speaks for itself. This is all pretty well established territory. Don't overthink it. Agree 100% with Jeff's comments. Hot days the sun is going to wear you out long before the car has a chance to....actually some friends here have said (with non-coyote motors) that the footbox gets REALLY hot in summer...
also, what about the trans tunnel? will the basic panel insulation be good enough?