If modifiers for movement aren't working for you...




As a right handed player...

I have my right hand on the mouse.
And my left hand accesses:
1 to 5
Tab to T
A to G
Z to V



As a left handed player...

Could you not have your left hand on the mouse.
And your right hand accesses the opposite keys, but the same number of keybinds?
8 to =
Y to ]
H to ;
N to /




I have WASD not set as mapped keys.
Which means they apply to the main/active window only.

If you had the arrow keys, not set as mapped keys.
They would also then apply only to your main/active window.

When I need the slaves to move independently...
I take my hand off of the mouse, and use the arrow keys, which are bound to slave independent movement.
You could do the exact reverse, and use WASD for the slave movement.

From the home row, there are as many keys accessible on the left or right side of the keyboard.
And they're as easily/hard to reach with either hand.