For heat rejection, we use the outside Adco Deluxe cover as someone mentioned earlier. Because it doesn't really solve the privacy problem, we also use an inner curtain around the inside of the cab on our 06 Seneca (Kodiak C5500). The interior curtain is not a good insulator, as the sun's rays still penetrate and heat the glass like an oven in there, on a hot day, and it radiates into the rest of the cab and the interior of the living quarters. The Adco does an awesome job! You may find the Heatshield does a good job as well, as it reflects. Unfortunately, the glass will still probably get hot and radiate.
2006 Jayco Seneca 34SS
2006 Jeep Wrangler Unlimited Rubicon Toad