Check these out. Portable - plug into the 12v power outlet and you can change lens colors from emergency to non emergency ambers or whites. Mount via suction cup, visor or hard wire.
http://www.yourhotcar.com/prod/ADS/P...ght_Visor/259/
And legality can be an issue. Believe it or not I have a golf cart with a blue rotating beacon light. I use it here at the private airport where I live. Anything that moves near the runway must have a rotating light for safety. I chose blue cause the cart is painted in a yellow and blue theme.
I took the cart to a hot air balloon event in SC last year to ride around on the field. On my way to a 5am pilot briefing on a stret closed to traffic I was stopped - and told very seriously that if the "Chief" had seen me I would have been ticketed. I was told it was against the law for anyone other than law enforcement to have a blue light on a vehicle in SC.
But a golf cart at 5am???? So be careful.