Maybe there is another option.
This reminds me of something I did when I made the mods to my Jackson many years ago.
One of things I did was to paint the set screws on the knobs white and use it as sort of a marker. I also installed pointers underneath the knobs, similar to a Les Paul. In this fashion, when the white dot is lined up with the pointer, the control is at max.
Even if your bass player doesn't want to install the pointers, putting a dab of paint on the knob would at least give him more of a reference than no markings at all.
Just an idea.
But, yes, I also get your point about not adjusting the controls. I'm just trying to figure out a way to let your bass player have his cake and eat it too!
This reminds me of something I did when I made the mods to my Jackson many years ago.
One of things I did was to paint the set screws on the knobs white and use it as sort of a marker. I also installed pointers underneath the knobs, similar to a Les Paul. In this fashion, when the white dot is lined up with the pointer, the control is at max.
Even if your bass player doesn't want to install the pointers, putting a dab of paint on the knob would at least give him more of a reference than no markings at all.
Just an idea.
But, yes, I also get your point about not adjusting the controls. I'm just trying to figure out a way to let your bass player have his cake and eat it too!