I didn't have a chance to read any of these but great idea OP
I overflow vessels with water all the time! Just this weekend I narrowly escaped disaster twice. I have a small powerhead in my topoff reservoir which I use to fill my mixing tank from. It's a slow fill and I've forgotten about it several times. This time the 90g reservoir ran dry with the 20g mixing tank filled right to the brim!
Then later that day I forgot to reset my rodi timer for a few more hours and was downtairs for some other random task when I remembered to shut the unit off with half an inch to spare.
I'm not to be trusted with water.