Well, for reference, here is the only way I was able to get just a 9V battery in an unmodded CCM 45 frame:
The stock CCM grips are a bit thicker than how far the battery sticks out. So I think it can work, but the battery connecter might be a PIA.
Ideally, I think I would like the microswitch to sit right below the sear without having to remove any metal. Otherwise I would have to devise something that would extend down the spring tube and mount the switch on the spring base.