tracking

I'm interested in doing a bit of spying on my Aldabra tortoises so I'm in the market for a trail camera. I specifically want to see how often, if at all, my tortoises are visiting the pond I made for them. I have never purchased a trail camera in me life so I'd really appreciate some feedback...

Where would be the safest place to put one of these on a tortoise? If it makes a difference, I will be placing on Red-footed Tortoise about 6" long. https://www.thetileapp.com/en-us/store/tiles/sticker