Very nice pics. You can make out the 3 PIR sensor pins (through hole) at the top, just left of the black sticky tape.
The fact that the PIE has 3 pins (and not some other number) indicates that they are analogue output (could be this one or this one. This means the electronics are easy to modify to turn the camera into a slave unit, but turning it into a master will require more sleuthing with no guarantee of success. You can see here for tracing details. Briefly, you can apply a voltage at pin 2 to trigger the camera. The circuit here built as a receiver will do just that.
The above is about modifying the electronics. Modifying the enclosure mechanically is a different story. I can’t say anything about that, not having the unit in hand.