I know you didn't state it. I was stickin it to ya.
As for the knob, I wasn't speaking about the knob, I was speaking to the sweep of the device. Look at the example below:
The green is the sweep of the device. The shape in the middle is the knob (same size for both pots). Just the pot itself is larger allowing for a longer, more precise sweep. I think it could still be hidden.
It's your project though. Sliders on mixing consoles work too... just sayin. Or an old Kenwood, Alpine, or Pioneer 1/2 DIN eq.