I think that it would fall under the same rule that says 'if you have a VHF on the boat it has to be on while underway'. ( or something to that effect )

I could see you taking to the coast guard telling them but it's not your primary navigation light but only for fun.

I tried to convince the harbor patrol here in Dana Point that my RIB tender with 15 Hp Yamaha outboard doesn't need navigation lights at night because it's against the law to go faster than 5 miles an hour in the harbor and I don't break the law, so the rule that says 'if you're unable to go faster than 7 mph you only need a 'white light' would apply to me. (the Admiral was holding a white light above her head)

They chuckled, let me off, called me a 'smart ass' and said "next time". I thanked them and now have running lights on the dingy.