@SmartHomePrimer - as you said to me earlier: 
Stove Safety Mod is done! And if I may say so, this may result in words and phrases like "genius!" and "What an ego that guy has!" being bandied about. 
Starting point - 6 burner gas stove.
Remove knobs and front panel:
Plenty of room behind the front panel to hold the contact sensor.
Plenty of room in the knob to place the magnet.
Magnet taken from magnetized hooks we had on hand. Use plumbers putty to hold the magnet in place.
Position sensor on back of the front panel so that it overlays part of the opening where the magnet on the knob will be positioned so the contact sensor reads Closed when the knob is in the Off position.
Holding the knob w/magnet in place on the other side so I can see what my clearances are. Confirmed it's working - sensor reads closed.
Looks like this from the front.
Four sensors mounted. I only wanted to monitor the four burners we use for longer-term simmering. For some reason/habit that's the front three and the left-rear.
Made sure batteries are easily accessible (not blocked by any flanges or other protuberances. This is the main "gotcha" - will have to take off the stove front panel to change batteries. Takes 8 screws and about five minutes - not a huge deal.
Also ensured all sensors had fresh 100% batteries installed.
Had my son help me hold the panel in place and tested each burner (installed knob with magnet) before really sealing things back up. BINGO!!! Houston, we have liftoff!
Burner on:
Contact sensor open:
Looks the same as when I started. No wires, no dangly bits, nothing to fall off, or get moved accidentally, or catch fire/melt.
WAF is running at 100%. 
Really happy with this (so far).
Now time to make automations - will be making some lights change color and have some voice announcements ("Then left burner has been on for 20 minutes."), etc.
Light strip on, letting us know one or more burners are on. It's intentionally set to a reduced level in this shot. We still haven't settled on how bright we want it. The good news is that it's very noticeable in person, even at this level during the day.
