I have seen people run them on their booms and on the inside of their hulls etc.... AS longs as the registration is current I don't think they care

Here are the regs...

The vessel registration number (CF number) issued by the department must be displayed as follows:

• Painted on or permanently attached to each side of the forward half of the vessel.

• Be in plain vertical block characters of not less than three inches in height.

• Be arranged so that it it reads from left to right.

• Contrast with the color of the background so that it is distinctly visible and legible.

• Have spaces or hyphens that are equal to the width of a letter other than "I" or a number other than "1" between the prefix and the number, and the number and the suffix. See the example below.
  
  Example: CF 1234 AB

BTW, was that you I saw out last weekend? If so I was the plane circling over top...