I don't think that the approach of modifying the class, rather than an instance, is a good idea. I also worry that private tools are not being configured at all (specifically, the MdtCalibrationTool and MdtCalibrationDbTool). Attempting to fix this.
This meant that I needed to make quite a few other changes, because it turns out that in many cases private tools weren't explicitly configured.
PLEASE MAKE SURE THIS IS SQUASHED the commit history is a big mess but I'm not sure I can face trying to clean it up now.