This is an old thread now and you've probably already found your answer, but I'll add my experience with the Pluto trigger.

As Jeff said, it's not waterproof. My idea was to put it inside the housing with the camera, either looking through the UV filter I used on the housing or through a small piece of acrylic. Unfortunately, it won't work through the filter, or the acrylic, so I've resorted to just having it looking through an open hole.

As far as power is concerned, it can be powered by any USB power bank, so that's not a problem.

Steve