Permanently removing the ears on the P12 doesn't look that hard.
1. Unscrew the tailcap from the light.
2. Remove the switch mechanism: I don't have the P12, but from the pictures it looks fairly standard. There should be a retaining ring on the inside of the tailcap around the spring that has 2 little holes in it. Insert something into those holes and turn to unscrew the retaining ring. You can use needle-nosed pliers, or snap ring pliers. If you don't have those, bend a large paperclick so the ends sit in the holes and then use long-nosed pliers as a wrench to turn the paperclip. Once the retaining ring is removed push down on the switch boot to push out all the internal switch mechanism. You should be left with just the metal tailcap with nothing in it.
3. Put the tailcap in a vise, take a hacksaw and saw off the ears. then use a file to soften the sharp edges.
4. Reassemble the switch mechanism.
Be warned that if you do this, the light will no longer tailstand so can no longer be used as a candle.
Suggestions for a proper tactical light? I don't have one so I'll have to leave that to others. My understanding is that it is best to have a light without mode memory or that has a shortcut so will always come on in max power. I've also seen suggested that the light only have a momentary mode so only turns on while the button is held down.... That way the user can briefly turn on the flashlight to illuminate a target, then release the button and immediately change position.