Temprature regulation in the cap

As I wait for my new shell and BedRug to arrive, I'm considering set up options. My previous truck was black and the covered bed /cap got pretty toasty in the summer if the truck was in the sun. Current truck is silver, cap will be silver too. The cap will also be lined. I'm considering getting a body shop to apply a metallic / reflective wrap on the roof of the cap in between the Yakima rails in an attempt to keep the temperature lower. Anyone ever done something like this or similar? Any other suggestions for temperature management?

 

They will help a tad, but it will still get hot in there. I’ve laid one of those silver reflective blankets over the top just to see what would happen and it still got unbearably hot in there (ambient temp just over 100 degrees)
A big problem is circulation. If you don’t have a way to get cooler air in and hot air out, it will always get hot

 

Thanks. Not the answer I was looking for, but also expected.