Ok, after much pondering over the situation, how about this. It would be expensive to replace the breaker in the mains panel with a GFCI breaker and you would still end up with a 3 wire system. Replacing the wire and the outlet adds a lot more to the build cost. Your place is also a rental so getting it done becomes a huge issue.
So with that all said, you buy a Spa Panel from homedepot.com - GE 50A Spa Panel
Then wire it using a dryer power cord. You wire it like this:
Or looking at a Spa Panel:
You can mount a 4 wire outlet directly into the panel so that your brewery controller can be plugged into it.
For a little more that 50 bucks you are ready to go on with your brewery control.