I remembered a thread about registering a 3 wheeler in Germany, but as I do not speak German I am not sure if insurance is covered in this topic. This may be of help tough!

http://www.talkmorgan.com/ubbthreads.php/topics/140773/M3W_oder_die_Kunst_ein_Dreirad#Post140773

Charlie, Former Editor
Morgan Owners Group - Great Lakes