I'm not up to speed on German regulations regarding single crew operations on the King Air. However, In the UK its the operator who specify whether they intend to use the Be200 single pilot or multi crew (or both in some cases), this is then endorsed on their UK AOC IIRC.
I'm guessing but I would think that, because your employer is requiring you to be TRed, then you are going to be conducting multi crew operations. It's quite common for corporate sized aircraft type ratings to be conducted in the United States, they are done under JAA requirements and usually have the facilities to do the MCC as part of the course again fully complying with (and usually exceeding) JAA regulations.