Detracting Numb3rs

[DFV]

Greetings,
My buddy has moved his sailboat from Ontario, CANADA to Point Roberts Marina, USA, ...just across the border from Vancouver, BC. I'm sure he has to switch to US registration numbers (the ones, 4" high on the outside of the hull). Do these numbers have to be on the bow? How does one put on an attractive boat name when these numbers have to be there as well? Can they not be placed on the stern, port and starboard? Can the Canadian number registration be kept?

-rg-