Here's the steps to turn off the MBPr screen with the lid fully open.
Remember as the instruction states once you enter in the commands in terminal you have to close the lid on bootup and restart and waking up from sleep mode. Once the logo screen appears you can reopen the lid and the screen will be off. (e.g., bootup: immediately close the lid, login screen appears, then you can open the lid)
Now you internal temps should be much much lower and the fan shouldn't kick up.
To execute in Terminal:
sudo nvram boot-args="iog=0x0"
To undo in Terminal:
sudo nvram -d boot-args
Once you type it into terminal I believe you need to enter your password. I then restart my machine. Now the TRICK is to either restart your machine with the lid already closed (hit restart then slam the lid!) OR turn the machine on for the first time (then quickly slam the lid!) once you are past the login screen you can open the lid.
ALSO: if the machine is asleep, and you simply forget and open the lid, it will wake up both displays. So just remember to wake the machine up with an external bluetooth mouse or keyboard.