Wow, that's a coincidence. I just got an EQ02 5K to drop into my fretless, except that it won't quite fit the control cavity and the cavity will also need to be enlarged if I want to put the bass filter stack knobs where I want to put them.
My bass has currently got a separate battery cavity and control cavity, and I've already worked out that if I route out the cavities and join the two, I will get what I want. As I saw the work on your control cavity I thought "mmm that's what mine will look like when I join the two cavities together', then to find out that it's driven by the need for EQ02 fitment....