Lighting a mobile billboard

Bedfin Mobile Billboards are pickup truck mounted signs. I am currently looking for information on legality in the USA for driving with the system illuminated. I understand the high intensity portion of the light beams shall not make contact with the eyes of onlookers. What I am curious about is if just having the sign face illuminated would get in the way of 50 state legality. Does anyone have any input or resources they can cite? Thanks