Same happened to me on new years day.I did boil more aggressive than usual.

Just etched my 20 gal brew pot in 1 gal increments and only labeled 5, 10, 15 gal marks . Any more would be overkill considering my brewing habits. Worked great but I used a 12 volt battery, much faster.

Fermentation then to secondary then to the keg for conditioning is my plan.

I want to use a half keg for lagering due to space restraints in my lagering fridge . I have a pulley system to lift the keg in and out of my chest freezer. I can purge the keg with co2 before lagering with no pressure but sealed.

Is there a right way or wrong way to lager? I lager in bottles , mini kegs and now want to lager 10 to 12 gals in a stainless half keg. Question is should there be a layer of co2 on the beer while it's lagering? I would think so , what are your thoughts?