Agree with AndyJWest, you need to be able to use both the aileron and the rudder at the same time. Here are some alternatives:
- Use the mouse-wheel, if you use the mouse to look around
- Use the keyboard left-right arrows, if your free hand is usually on the keyboard
- Use two buttons on the joystick itself for left rudder and right rudder, if your free hand is on the joystick base

None of those are better than a twist-stick or pedals, but you should find them all easier to implement than your idea.

Take it back and get something with a twist rudder. Start planing your next move... Pedals, HOTAS and most importantly TIR. Good Luck!