You are limiting yourself to CONTROL and SHIFT you don't see any other buttons on the keyboard.
If CONTROl of SHIFT is not ok then "Z" or "X".

And Valkyrie_Lenneth did you thot about using YGHJ instead of WASD ? I know ppl that do just so they heave more kye's around their fingers and don't need so many macros or they can use keys around their finger to do more macros.
You are dismissing my Suggestion because some ppl including me atm are using SHIFT and CONTROL to bind it with the number keys.