The running costs could be cut down quite a bit by only uploading when it's actually necessary: only start uploading if a sensor is triggered and the 'do not upload' button is not subsequently pressed.
I've played around quite a bit with a computer vision library (OpenCV), which can be trained to faces much better than you'd expect -- it'd be interesting to just squelch photos with known faces. So that you only have to deal with the 'do not upload' button if strangers are aboard.
Or put the DVR in a hidden strong box, and start uploading if the panel to the compartment it's in is opened. Figure it takes n minutes to breach the box, then aim for n/2 minutes to upload the recent photos. Maybe first upload the photos with unknown faces, then fill in the rest as time permits.
I feel it's unlikely a warning sticker would do anything. The purpose would mainly be to ensure people are properly identified. Maybe the nuttier among us could pull a McAfee and setup an offshore
trust that automatically, and posthumously, funds a hit on those responsible with a couple hundred grand.