Just in case anyone is interested, and to follow-up on progress:
I've pretty much finished the prototype camera-based controller and it's working well. Attached photo shows what I've done (please don't laugh - I live in a rural area and am a bit mobility challanged - not easy to get out to "Get stuff" - I will rebuild the final devices in better "enclosures"):
I was able to make it evem better than I had first envisions. I thought I would have to run the microcontroller 24/7, but in the updated design the only thing "always active" is a little 10v transformer (little can in center) and rectifier - no electronice other than one ID detector and a CR-2032 solid state relay.
Top left is the main controller - I had some card sets from an RS-232 data-switch I designed many years ago, and just tossed together a little "fake backplane" which gives me the CPU (6809, 8kROM, 48kNVRAM) and one serial card (8x 6551 serial ports). Since the ram is NV, I just have my MON09 debug monitor in the ROM, and modified it to detect a valid application in RAM and auto-start it.
Center is the "power controller" - it uses the IRled to the right of the camera to detect when to turn stuff on (via a CR2032 solid state relay). This turns on an area light as well as the main controller. The controller starts, and it's interface to the power controller is very simple - it just asserts a signal to hold the CR2032 ON (so the camera can do other things), that same signal also lights the LED to the right of the camera which gives visual feedback that the controller is up and active.
Top right is my "server" - a small-form-factor Dell-I5 I got free because it's internal "unobtanium" power supply had failed - as you can see I "grafted" a standard ATX supply to the side, and using the deadPS connector, made an adapter. The only reason I'm showing this is so that you can see the connection I added to it which gives external digital access to the front-panel power button and it's internal 5V active rail (so the main controller can turn on/shutdown, and tell when it's operating) - this connector connects to:
Lower right is the "server controller" - very simple, it can "press" the server power-button, and detect if the server is up.
Lower left is the "camera mount" - It has a couple IR detectors I can point the camera at and "press" by turning On/Off IR "night vision". It also has a couple visible LEDs hanging out behind which provide feedback to the camera, making it possible to selectively perform functions like "turn on the server", control pumps etc.
Once the server is up, I can connect to it remotely with AnyDesk, peruse the local cameras, do other functions (the server can do X10 power control)....
At the end, all I havde to do is "shutdown" the server. The main controller will notice that it has, and will drop it's activation of the CR2032, therby shuting itself down.
The main controller can perform appropriate timeouts etc. and can gracefully shutdown the server and itself as needed (going to have lots of fun writing the controller firmware)
And... yeah, I know this could be done with modern stuff, much smaller... but I just love building stuff out of the 40+ years worth of jun...xxx fine high-quality surplus equipment I already have in my basement!