Doesn't a guy here have a bass with that exact combo?
A MM should have a much hotter output than a single coil P.
I wouldn't recommend having two tone controls in a passive circuit.
Due to the nature of the wiring, when the pickups are at an equal volume, the tone controls are in parallel, so whichever one is at the lower setting will affect both pickups.
There are only two ways around this:
You can isolate the tone controls from each other through the use of two 220K resistors, however, this equates to a huge drop in volume, the resonant frequency is shifted downward and the treble is decreased.
The only true way to have functional, independent tone controls is to actively buffer the circuits from each other.