Not really what I am asking for though but thank you!

Still, just to reiterate again. I would like a hotkey to immediately start drawing out a rectangle. That's it.

I just wanted to come here to say exactly this. I currently use SnagIt cause it has this functionally. I have a hotkey to go straight into drawing a region on screen to either screen record/screenshot. I want to use bandicam cause it can record at 60fps and it has everything I want except the hotkey...