Rigged it up as suggested. Filled the pot with 6+ gallons of water and it drained again opening the spigot. It stopped at the same place, the bottom of the outlet pipe, did not acheive a siphon. Fittings were pretty tight, but no teflon tape or solder was used inside the kettle.
I guess it would work if I used a march pump to drain out the everything below the invert of the spigot?
I'll post photos.

