This might be an @Al1885 question.
So… let’s say that I have a solidbody Kala U-Bass. Let’s also say that I have a set of passive P/J EMG pickups. If I wanted to install JUST the P pickup from that passive EMG P/J set… how would I go about hooking that up? Is it possible, to install only the split-coil and not the full P/J set?
Yeah it is my kind of question 
. You could just use the solderless connector to the pickup then splice the other end to the existing preamp with the heat shrink solderless tube. It’s that simple.test it with alligator clips before committing to anything, don’t ask me how I’ve come to that wisdom 
These are the solderless passive pickups, there’s no pre-amp or anything.
There’s plenty of room under the pickguard if you change your mind.
It’s not the pickup, it’s the string. The set that comes with the solid body is not exactly made for such scale, you’d have significant amount of overtones. Check out Dogal string. It’s not cheap but it’s super awesome string which makes your solid body sounds like a regular P bass.
