Instead of S3, it may be possible to do "small computer with harddrive hidden inside the house (furniture, walls, ceiling, etc) tapped into a power-line and con

Instead of S3, it may be possible to do "small computer with harddrive hidden inside the house (furniture, walls, ceiling, etc) tapped into a power-line and connected over wifi. Their options for finding that would be limited if they did not bring equipment to triangulate wifi devices with them. Limited to methods that would certainly leave a trace of their presence. If you set the camera up correctly, it might not even be immediately apparent that they had to look for the storage device (give the camera plenty of storage of it's own, so that it seemed likely that the images were being stored on the camera.) Sure, they might come back next week with the equipment they need, but in the meantime you'll have your photographic evidence and a few days to go public with it.