I have a small crock pot.highest temp I get with that is 140.My insulated wooden box looks a little smaller than your fridge. The main reason I am looking into compressed bricks for curing etc.
Running mine with crockpot on low setting, I could easily have a stable temperature between 125-135F with RH 70-75. I have a vent at the top to control humidity. Hardly need to touch it.
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With no water in crock pot, it got to 167F on high setting which seemed close to the max. I don't believe flue curing is an option running a crock pot dry and on the high setting for too long.
Removing the knob on the crock pot lid, enabled me to insert the tubing to keep the water level topped up. This way, I have great control to keep the humidity down should I need to.