I map as many buttons to the controller as possible. I do this to make playing easy.
I set scroll wheel for toolbar and scrolling menu.
Bumpers are for loading and saving toolbar in creative mode. I figured loading is used more frequently than saving, so I put loading toolbar on right bumper.
I also map jumping to left grip, so that you can jump while aiming.
The keyboard is buggy though, it inputs 2 letters with one press. It will be better if the bug is fixed.
Note that you can add other controls to the radial menu.