Build a 6” x 6” MK III terp.
With a 12” or 18” x 1.5” material column.
Recover passively.
Outdoors.
Leave sources of ignition elsewhere
Glacier tanks + BVV will have all the parts. Read up on how to run it.
You’ll need a vacuum pump. And ideally remotely heated circulating hot water. My first circulator was a 120V hot water heater element mounted in 2” black pipe (steel water pipe). Pumped with a small mag drive pump I pulled out of a dumpster.
The PID controller, enclosure, and 40’ of heater hose & insulation probably came to less that $200. Circulated through an insulated keggle I had lying around.