Human psychology is a funny thing. Put a "smile your on camera" sticker but don't actually put a camera.
I put a small sign in the back of my van next to the camera (post 763)
https://dashcamtalk.com/forum/threads/where-did-you-mount-the-camera-post-your-pictures.502/page-39 The obviously handmade sign says "Smile for the camera" and under the arrow pointing to it, it says "Here's
ONE" which hints at there being others. Also some "BS" regarding it being uploaded to the cloud
Not in those linked pics but now in the van if you look deeper inside you'll see a G1Wc facing back on top the right shelf. Yes, you can cover the first cam but the second one sees you doing that
Unseen is that the second rear cam doesn't work but you can't tell that by looking
That is the only sign and only indiscreet cam in the van. The thieves (and general population) here aren't terribly bright folks but almost all of them can read.
My intent was to get people off my rear bumper and it's been working pretty good where tailgaters have time to see and read the sign. It also gives me some security against theft as the stupid thieves around here will believe the "uploaded" part and that the second cam has got them already
It wouldn't be as effective in places where people know about dashcams, but I'm pretty much a 'pioneer' with them here. Next will come an alarm system and then I'll be as safe against theft as I can be. My situation is unusual in that I park and work in some less savory neighborhoods sometimes and I'm already a target for theft with all my tools, so having that visible cam and the handmade sign works for me instead of against me. A plastic sticker would be prettier but thieves know that for 100 alarm stickers 99 of them have no alarm to go with them. In my case they can see it's not all BS- there's certainly a cam or two there, I took the time to make my own sign pointing this out, and god knows what else I've got going so they'll leave me alone I hope.
If most people where you drive know what dashcams are, I'd just buy the cheapest one Gearbest or Banggood sells and wire it in. If it works, fine. If it dies, it still has value in making people think it works. And the cheap ones usually have a useless white LED on the lens side that will make it seem real enough. Should be under $20 US total including shipping and as a deterrent it's a believable bargain versus a simple obvious sticker-scam with a faked cam. Know your enemy and you'll know how to keep them at bay
Phil