This. If you forget to unplug the lead you'll probably forget to pull the knob, flick the switch, do the secret handshake, flood the tanks, batten down the hatches and whatever other solutions which require manual intervention. You've just gotten into a habit and are looking for a technical solution for it which, to me, seems like the wrong way to go and destined to fail regardless which way you choose to get around it. Just change the habit. Regardless of the bass, get into the habit of unplugging when you have finished. You don't have to do anything else, leave the lead hooked in the strap so it's right there when you want to play again. Just get into the habit of unplugging the bass when you stop playing, whether it's active or passive. It'll become second nature in no time at all.