[Smidgelton]

I'm no luthier, but I think it goes beyond swapping pickups and connecting a few wires. There is the onboard preamp you have to install. Yes, you will need a place for the battery which would mean cutting into your bass. Also, an active pickup system has an active EQ and a typical active bass has at least 4 knobs, sometimes 5 (the fifth is usually just a pickup blend knob). 4 knobs dedicated to volume, treble, mids, and bass. That may mean more holes to drill in your bass depending on how many knobs you have.

Then there is the question... is the bass even worth it to put work so much work into? Buying a better bass (not necessarily active - because active doesn't automatically mean better) may be a better move than putting a lot of work into an "okay" bass.

There is probably a more practical solution than this.