RE: looking for walk in unit
I am in a different industry than the restaurant guys but all of our business's use walk in freezers that cool to -40F. These are currently costing us about $40K each plus installation.
Most major refrigeration companies have the ability to assemble or disassemble freezers. That is the easy part. Hooking up the compressors and tuning them is the issue.
We also use recorders to document our temps 24-7.
Paul E. Smith