My suggestion is do what I did on mine. I had the back windows tinted over, because the factory tinting doesnt reflect heat anywhere near as well as aftermarket tint will.
I tinted the front 20% and tinted over the back 35% (should bring the back windows down to about limo black 5%)
Heres a pic
Sounds like you might want about 15% up front, mabey darker to get it to match, but I am in TX too, so i suggest doing the back windows over to keep your cab cooler.