Re: Registration Number Legalities
In all 50 states the legal requirement for registration numbers is a minimum height of 3" tall in "roman" or "block style" characters. They must also be in a contrasting color to the background where they will be applied.
Most states require a space between the letters and numbers equal to one, sometimes two, character spaces. While some states, South Carolina for example, require a dash between the letters and numbers instead of a space. Examples: FL 1234 AB or SC-1234-AB
Outlines, shadows, slants or all of the above can be used as long as the registration numbers themselves are still 3" tall and contrast with the background color.
In my 20+ years of making boat lettering, I have found that as long as the registration numbers are legible from at least 20 feet away you shouldn't have a problem.
~ the Cap'n