calling @ki0g0n
John makes excellent controls for passive basses and is more qualified than most to weigh in here.
I'd go with a 500kΩ pot and a 47nf capacitor, but that's just my taste. depends how much of the top end you want to roll off - a smaller value capacitor (e.g.22nf) will allow more top end through when the tone control is at 0%.
Yup. I'm not playing live anywhere near as much as I used to, so periodically running through setlist for bands I occasionally dep with helps me keep my piggies wriggling and also makes sure that there's less 'cramming' to do when the dep gigs come in.
Bass (mostly fretless Jazz) - pedalboard - zoom 607 as a headphone amplifier, I’m toying with an EHX headphone amp as they’re battery powered too, and significantly smaller. The 607 is a lot of fun though.
an iPhone on the same wifi network as this will work as a remote control. We have to do this when our remote periodically goes missing - often down the back of a sofa.