One more thing...
You won't be needing two mini switches. The Bartolini HR-5.4AP/918 preamp comes with a mini switch functioned as midrange frequency selector. So, you'll only have 1 more hole to fill.
Actually, if you can get the special version of HR-5.4AP/918 preamp, which comes with another mini switch for preamp bypass like the stock Ibanez preamp, you'll have all holes filled. This special version used to be available on bestbassgear.com (probably still is if asked).
Another option is to fill the extra hole with an on-off-on DPDT switch for coil switching of the MK5CBC's. With this single switch, you can have the two pickups run as single outer coils, dual coils, and single inner coils for more tonal options.
You'll only be needing two mini switches if you opt for the HR-5.2AP/918, which doesn't come with any mini switches (it uses another push-pull potensio for mid freq selector instead). This opens up for another kind of coil selections for the MKCBC's. The two mini switches can be individually assigned for for each MK5CBC, of which if they are the on-on-on DPDT kind of types, they can give you the options of parallel dual coil, single outer coil, and series dual coil.
