Do you really want to hide the wiring, or would you rather have it out where you can see it, inspect it and maintain it? No wrong answer here, just wonderin'. (Most cyclists don't seemed to had any problem with exposed brake and gear cables for the last, oh, 110 years or so.)

BTW, here's the owner's manual recommended set up for the 1920 Bulli rim drive dynamo with battery powered stand light: