I can't seem to come up with an ideal configuration at the moment.
My default for most PC games is a gamepad (left hand) and mouse (right hand).
I use Xpadder
to map the WASD and other default keys for movement to the left thumb stick /buttons of the gamepad, and use my mouse drivers to map weapon keys to the mouse wheel. Then because RS has a few more keys, I put team control ("Go-Codes" etc) on the right thumb stick /buttons. I can reach my left thumb across to edge the right stick, and just rest the gamepad on my knee to hit the other buttons, or take my hand off the mouse. This way I have everything covered and do not even need to touch the keyboard. (For me gamepad + mouse is a lot more natural to control movement, and far easier to use than fumbling keys, while also helping to remember which key does what).
I guess a picture might be worth more... (These are in-game default keys, although I think I changed left-shift to "run" and right-mouse to "sniper zoom")
Unfortunately, I got a little sick of the game because the friendly AI isn't that great at using flashbangs. It was a struggle. Sometimes, my custom plans worked flawlessly, but most of the time everything went tits-up as soon as one of the friendly squads approached their first closed door.
Still, thanks for the input. Maybe I'll give it another short in the near future, especially since Takedown offers little to no focus on single player.