Two cents taken, I can get a second Brewtroller board and repurpose it to run the fermentation. Perfect!
As for protecting the heating elements. I work with waste heat boilers that produce 600# steam. The equipment is protected by low level and low-low level sensors. I was going to have a float switch for a low level that would turn on a light on the control panel and then another low-low level float switch that would cut the power to the heating element. I will also have on the boiler a borosilicate sight glass that is protected by a stainless steel tube sleeve.