US Coast Guard Regulation

[dubob]

I would love to challenge the LEO on where he got the 5 mph.

Ahhh - you would lose the challenge.     He got it from the Utah Code which defines wakeless speed thusly:

"Wakeless speed" means an operating speed at which the vessel does not create or make a wake or white water trailing the vessel. This speed is not in excess of five miles per hour.

I think a person would be hard pressed to prove to a judge that an LEO was mistaken as to observing a 'wake or white water trailing the vessel' absent a radar speed measurement.  It will be your word against the LEO's word in the courtroom.  Hmmmm - who wins that one?